Module (1-4): Forensic Sciences Laboratories and Techniques(CRIME LABORATORIES), Exams of Forensics

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Module 1: Forensic Sciences Laboratories and Techniques PowerPoint CRIME LABORATORIES ➔ Ever increasing # of crime labs is partly the result of: ◆ Supreme Court decisions in the 1960s responsible for police placing greater emphasis on scientifically evaluated evidence ◆ Crime laboratories inundated with drug specimens due to accelerated drug abuse ◆ The advent of DNA profiling ➔ Centers for Forensic Investigation of ◆ Ongoing Criminal Cases ◆ Research into new techniques and procedures ➔ United States ◆ development of crime labs in the US has been characterized by rapid growth accompanied by a lack of national and regional planning and coordination ◆ At present, approx. 411 public crime laboratories operate at various levels of government -- federal, state, county, and municipal ➔ Canada ◆ RCMP Forensic Laboratory services ◆ Provincial labs ◆ Few private labs ◆ Centre of Forensic Sciences ◆ Central lab in Toronto ◆ Smaller regional lab in Sault Ste. Marie ONTARIO CENTER FOR FORENSIC SCIENCES ➔ Part of the Govt. of Ontario Ministry of Community safety and correctional services ➔ Provides Forensic Sciences services to law enforcement agencies in Ontario ➔ One of the most extensive Forensic LABS in North America ➔ 1993: became the 1st Forensic lab in Canada to be accredited to an international set of Standards CRIME LAB SERVICES: BASIC SERVICES ➔ Physical Sciences Unit ◆ Incorporates the principles of chemistry, physics, and geology to identify and compare physical evidence ➔ Biology Unit ◆ Applies the knowledge of biological sciences in order to investigate blood samples, body fluids, hair, and fiber samples ➔ Firearms Unit ◆ Investigates discharged bullets, cartridge cases, shotgun shells, and ammunition ➔ Documents Examination Unit ◆ Provides the skills needed for handwriting analysis and other questioned- document issues ➔ Photography Unit ◆ Applies specialized photographic techniques for recording and examining physical evidence CRIME LAB SERVICES: OPTIONAL SERVICES ➔ Toxicology Unit ◆ Examines body fluids and organs for the presence of drugs and poisons ➔ Latent Fingerprint Unit ◆ Processes and examines evidence for latent fingerprints ➔ Polygraph Unit ◆ Conducts polygraph or lie detector tests ➔ Voiceprint Analysis Unit FUNCTIONS OF THE FORENSIC SCIENTIST ➔ Analysis of Physical Evidence ➔ Providing Expert Testimony ➔ Furnishing Training in the Proper Recognition, Collection, and Preservation of Physical Evidence IN A NUTSHELL ➔ Forensic science = application of science to criminal and civil laws that are enforced by police agencies in a criminal justice system ➔ The development of crime laboratories in the US has been characterized by rapid growth accompanied by a lack of national and regional planning and coordination ➔ The technical support provided by crime laboratories can be assigned to five basic services: the physical science unit, the biology unit, the firearms unit, the document unit, and the photography unit ➔ Some crime laboratories may offer optional services such as toxicology, fingerprint analysis, voiceprint analysis, crime scene investigation, and polygraph administration ➔ A forensic scientist must be skilled in applying the principles and techniques of the physical and natural sciences to the analysis of evidence that may be recovered during a criminal investigation ➔ An expert witness evaluates evidence based on specialized training and experience ➔ Forensic scientists train law enforcement personnel in the proper recognition, collection, and preservation of physical evidence ➔ The Frye v. United States decision set guidelines for determining the admissibility of scientific evidence into the courtroom ◆ To meet the Frye standard, the evidence in question must be “generally accepted” by the scientific community ➔ In the case of Daubert v. Merrell Dow Pharmaceuticals, Inc., the U.S. Supreme Court ruled that trial judges were responsible for the admissibility and validity of scientific evidence presented in their courts REVIEW QUESTIONS ➔ List three main reasons for the wide variation in total services offered by crime labs in different communities ➔ Describe the basic duties of the physical science unit in a crime lab and give three examples of the type of work performed by a physical science unit ➔ In addition to the physical science unit, what four units typically are found in full-service crime labs? ➔ List at least one function performed by each of these units ➔ List two optional units found in most crime labs and give at least one example of the type of work done by each ➔ List the main functions of the forensic scientist ➔ What important principle was established in the case of Frye v. United States? ➔ How did the court’s ruling in the case of Daubert v. Merrell Dow Pharmaceuticals, Inc. affect the admissibility of scientific evidence in federal courts? ➔ How does the testimony of an expert witness differ from the testimony of a lay witness? ➔ List two ways in which a forensic odontologist can assist in criminal investigations Module 2: Microscopy in Forensic Sciences INTRODUCTION ➔ Virtual image: the magnified image seen by looking through a lens ➔ Real image: image viewed directly A MICROSCOPE ➔ Microscope: an optical instrument that uses a lens or a combination of lenses to magnify and resolve the fine details of an object ➔ Earliest methods for examining physical evidence relied solely on the microscope ➔ The object to be magnified is placed under the lower lens, called the objective and viewed through the upper lens, called the eyepiece. ◆ Lower lens = objective ◆ Upper lens = eyepiece ➔ Various types of microscopes are used to analyze forensic specimens HOW TO USE A MICROSCOPE ➔ Youtube video -- slide 17 COMPOUND MICROSCOPE ➔ In the basic compound microscope, the object to be magnified is placed under the lower lens (objective lens) and the magnified image is viewed through the upper lens (eyepiece lens) ➔ The magnification of the image can be calculated by multiplying the magnifying power of the objective lens times the magnifying power of the eyepiece lens ◆ Magnification = magnifying power of the objective lens (x) magnifying power of the eyepiece lens ➔ The microscope is composed of: ◆ a mechanical system -- supports the microscope ◆ an optical system -- illuminates the object under investigation and passes light through a series of lens to form an image of the specimen Module 3: Physical/Trace Evidence and their Analysis PHYSICAL EVIDENCE ➔ It would be impossible to list all the objects that could conceivably be of importance to a crime. ➔ Almost anything can be physical evidence ➔ Although you cannot rely on a list of categories, it is useful to discuss some of the most common types of physical evidence. ➔ The purpose of recognizing physical evidence is so that it can be collected and analyzed. COMMON TYPES OF PHYSICAL EVIDENCE ➔ Blood ➔ Semen ➔ Saliva ➔ All suspected blood, semen or saliva – liquid or dried ➔ Documents ➔ Drugs ➔ Explosives ➔ Fibers ➔ Fingerprints ➔ Firearms and ammunition ➔ Glass ➔ Hair ➔ Impressions ➔ Organs and physiological fluids ➔ Paint ➔ Petroleum products ➔ Plastic bags, plastic, rubber, and other polymers ➔ Powder residues ➔ Soil and minerals ➔ Tool marks ➔ Vehicle lights ➔ Wood and other vegetative matter PURPOSE OF EXAMINING PHYSICAL EVIDENCE ➔ The examination of physical evidence by a forensic scientist is usually undertaken for identification or comparison purposes. CLASSIFYING CHARACTERISTICS ➔ Individual Characteristics ◆ Evidence that can be associated to a common source with an extremely high degree of probability is said to possess individual characteristics ➔ Class Characteristics ◆ Evidence associated only with a group is said to have class characteristics FORENSIC PHYSICAL EVIDENCE ➔ http://www.videojug.com/interview/forensic-science-2 -- pot noodle FORENSIC DATABASES ➔ The Integrated Automated Fingerprint Identification System (IAFIS) ◆ a national fingerprint and criminal history system maintained by the FBI ➔ The Combined DNA Index System (CODIS) ◆ enables federal, state, and local crime laboratories to electronically exchange and compare DNA profiles ➔ The National Integrated Ballistics Information Network (NIBIN) ◆ allows firearm analysts to acquire, digitize, and compare markings made by a firearm on bullets and cartridge casings ➔ The International Forensic Automotive Paint Data Query (PDQ) ◆ database contains chemical and color information pertaining to original automotive paints ➔ SICAR (shoeprint image capture and retrieval) ◆ is a shoe print database TRACE EVIDENCE AND MICROANALYSIS ➔ Trace evidence- Qualitative or quantitative analysis of the minor or ultra minor components of a sample ➔ Sample- entire submitted exhibit or a subsample of the exhibit ➔ Microanalysis is the application of a microscope and microscopical techniques to the observation, collection, and analysis of micro evidence that can not be clearly observed or analyzed without such devices. ◆ Deals with samples in milligram or microgram size ranges. ➔ Large forensic laboratories are generally more specific; fiber, hair, mineralogy, paint, serology, firearms analyses, controlled substances. ➔ Small laboratories may be grouped differently, such as in sections of chemistry, biology, microscopy, drugs and ballistics. INSTRUMENTS OF MICROANALYSIS AND SAMPLE TYPES ➔ Microscopes are the first tool used to examine trace evidence ➔ Stereo binocular microscopes, compound in nature, are often used ➔ Lens – optical component that may be composed of one or several elements ➔ Stereo microscopes have 2 separate eyepieces, and views are separated by a small angle (15 degrees) ➔ Use of stereo microscopes allows for item being examined to been seen separately ➔ by each eye ◆ This creates the appearance of three-dimensions ➔ Stereo microscopes are normally used with reflected light ➔ Compound binocular microscope – second most common type of microscope encountered in laboratory ➔ Two eyepieces are present, however, both eyes see the same image ➔ This microscope often employs transmitted, bright field illumination STEREO MICROSCOPES MICROSPECTROPHOTOMETRY ➔ Instruments that generate transmission, reflection, or adsorption spectra from various translucent or opaque samples ➔ Principal types of instruments are visible and infrared ➔ Commonly used to analyze colored fibers or paint surfaces DISPERSIVE RAMAN SPECTROMETER SCANNING ELECTRON MICROSCOPE (SEM) ➔ A microscope that permits viewing of samples at much greater magnification and resolution than is possible by light microscopes ➔ Magnification is possible in the range of 10 to 100,000x ➔ When combined with a energy dispersive xray spectrometer, (EDS) this tool becomes invaluable ➔ SEM/EDS combination can readily resolve a particle smaller than 1 micrometer in size, while generating spectra revealing elemental size of object ➔ SEMs are more valuable due to development of low pressure or low vacuum systems which allow sample being studied not to be kept at such great reductions in pressure OTHER INSTRUMENTAL TECHNIQUES OF VALUE TO A MICROANALYST ➔ X-Ray diffraction ➔ Pyrolysis Gas Chromatography/Mass spectrometry ➔ X-ray fluorescence ➔ Atomic absorption ➔ Atomic emission ➔ Atomic Mass Spectrometry MICROSCOPIC EVIDENCE AND ITS ANALYSIS -- GLASS ➔ Glass is a common type of evidence ➔ Commonly encountered as transfer evidence ➔ Examination of broken glass can reveal whether the impact that caused the fracture was caused by low or high velocity blunt trauma (Coring Effect) ➔ ➔ Radial crack – those cracks originating from impact point and propagating away ➔ Concentric crack- those cracks seeming to make a circle around the point of impact ➔ Radial and concentric fractures . A series of impacts on glass . The sequence is indicated by the terminations of newer cracks at existing fractures ➔ Conchoidal Lines - those edge characteristics of glass fractures. They are stress marks shaped like arches that are perpendicular to one glass surface and curved nearly parallel to the opposite surface. The perpendicular surface faces the side where the crack originated ➔ When microscopic glass chips are examined, the following properties are evaluated: ◆ Physical – thickness, uniformity, color, curvature, surface conditions-tinting, soiling, etc ◆ Optical – most significant property is Refractive Index ◆ Elemental – composition of glass ◆ inductively coupled atomic emission spectroscopy ➔ Sample is considered when certain elements, normally barium and antimony, are found together above a baseline level ➔ SEM/EDS can be used to analyze possible gunshot residue ➔ Consideration in collection of gunshot residue and analysis should include possible environmental contamination, location of sample, and where sample was collected – web of hand, palm, other parts of the body, etc IN A NUTSHELL ➔ The size of the samples separates microscopic evidence from other evidence ➔ Microanalysis is the application of a microscope and microscopical techniques ➔ Instruments for microanalysis ◆ Stereomicroscopes ◆ Compound Binocular microscopes ◆ Microspectrophotometers ➔ Key Features of Microanalysis of evidences like: ◆ Glass ◆ Paint ◆ Soils ◆ GSR Module 4: Forensic Serology NATURE OF BLOOD ➔ Plasma, which is the fluid portion of blood, is composed principally of water and accounts for 55% of blood content ➔ Red blood cells (erythrocytes), white blood cells (leukocytes), and platelets are the solid materials suspended in plasma ➔ Antigens, usually proteins and carbohydrates, are located on the surface of red blood cells and are responsible for blood-type characteristics ➔ Plasma contains proteins known as antibodies ◆ The fundamental principle of blood typing is that for every antigen there exists a specific antibody ➔ Antibodies are normally bivalent—that is they have two reactive sites ◆ This means that an antibody can attach to antigens located on two red blood cells forming a network of cross-linked cells seen as clumping or agglutination AGGLUTINATION OF BLOOD CELLS ➔ BLOOD TYPING ➔ More than 15 blood antigen systems have been identified, but the A-B-O and Rh systems STEPS REQUIRED TO PRODUCE MONOCLONAL ANTIBODIES EMIT ANALYSIS ➔ In the EMIT assay, a drug that may be present in a urine specimen will compete with added labeled drugs for a limited number of antibody binding sites. ➔ The labeled drugs are indicated by an asterisk. ➔ Once the competition for antibody sites is completed, the number of remaining unbound labeled drug is proportional to the drug’s concentration in urine. FORENSICS OF BLOOD ➔ The criminalist must be prepared to answer the following questions when examining dried blood: ◆ 1. Is it blood? ◆ 2. From what species did the blood originate? ◆ 3. If the blood is of human origin, how closely can it be associated to a particular individual? ➔ The determination of blood is best made by means of a preliminary color test BLOOD COLOUR TESTS ➔ A positive result from the Kastle-Meyer color test is highly indicative of blood ◆ Hemoglobin causes a deep pink color. ➔ Alternatively, the luminol test or Bluestar test are used to search out trace amounts of blood located at crime scenes. ◆ Produces light (luminescence) in a darkened area ◆ Luminol is extremely sensitive and is capable of detecting blood that has been diluted up to 100,000 times. HUMAN BLOOD STAINS PRESUMPTIVE TESTS ➔ https://www.youtube.com/watch?v=pnH2HnB-GrI BLOOD ORIGIN TESTING ➔ Once the stain has been characterized as blood, the precipitin test will determine whether the stain is of human or animal origin. ➔ The precipitin test uses antisera normally derived from rabbits that have been injected with the blood of a known animal to determine the species origin of a questioned bloodstain ➔ The technique of gel diffusion takes advantage of the fact that antibodies and antigens diffuse or move toward one another on an agar plate. ➔ The extracted bloodstain and the human antiserum are placed in separate holes opposite each other on the gel. If the blood is human, a line of precipitation forms where the antigens and antibodies meet. THE PRECIPITIN TEST INDIVIDUALIZING BLOOD STAINS ➔ Once it has been determined that the bloodstain is of human origin, an effort must be made to associate or dissociate the stain with a particular individual. ➔ DNA analysis has allowed forensic scientists to associate blood to a single individual GENES AND CHROMOSOMES ➔ An allele is any of several alternative forms of genes at a particular locus and that are aligned with one another on a chromosome pair ➔ A heterozygous gene pair is made up of two different alleles; a homozygous gene pair is made up of two similar alleles ➔ When two different genes are inherited, the characteristic coded for by a dominant gene will be expressed. The characteristic coded for by a recessive gene will remain hidden been supplanted by newer DNA technology. ➔ The best way to locate and characterize a seminal stain is to perform the acid phosphatase color test. ➔ Forensic scientists can successfully link seminal material to an individual by DNA typing. Module 5: Understanding DNA in Forensics THE STRUCTURE OF NUCLEAR DNA ➔ Actually, a human cell contains two types of DNA-nuclear and mitochondrial. We will focus first on nuclear DNA ➔ Nuclear DNA strand is a very large molecule made by linking a series of repeating units called nucleotides. ➔ A nucleotide is composed of a sugar, a phosphorus-containing group, and a nitrogen- containing molecule called a base ➔ A nucleotide is composed of a sugar, a phosphorus-containing group, and a nitrogen- containing molecule called a base ➔ How nucleotides can be linked to form a DNA strand. ➔ S designates the sugar component, which is joined with phosphate groups (P) to form the backbone of DNA ➔ Projecting from the backbone are four bases: ◆ A, adenine ◆ G, guanine ◆ T, thymine ◆ C, cytosine ➔ The DNA molecule is comprised of two strands each wrapped around the other in the form of a double-helix ➔ The bases on each strand are properly aligned in a manner known as complementary- base pairing. ➔ As a result, adenine pairs with thymine and guanine pairs with cytosine DNA DOUBLE HELIX ➔ A representation of a DNA double helix. ➔ ´Notice how bases G and C pair with each other, as do bases A and T. ➔ This is the only arrangement in which two DNA strands can align with each other in a double-helix configuration DNA AT WORK ➔ Each group of three nucleotides in a DNA sequence codes for a particular amino acid ➔ ´Example: G-A-G codes for the amino acid glutamine, while C-G-T codes for alanine. ➔ ´If a nucleotide is “changed”, for example a T is substituted for A and G-A-G becomes G- T-G, the “wrong” amino acid is placed in the protein (in this case glutamine is replaced with valine). ➔ As a result, the protein may not function correctly and this is the basis for many diseases and health issues ➔ ´(a) A string of amino acids composes one of the protein chains of hemoglobin. ➔ (b) Substitution of just one amino acid for another in the protein chain results in sickle- cell hemoglobin DNA REPLICATION ➔ DNA duplicates itself prior to cell division ➔ DNA replication begins with the unwinding of the DNA strands of the double helix ➔ ´Each strand is now exposed to a collection of free nucleotides that will be used to recreate the double helix, letter by letter, using base pairing. ➔ ´Many enzymes and proteins, such as DNA polymerases, are involved in unwinding the DNA, keeping the DNA strands apart, and assembling the new DNA strands in the proper order (A with T and G with C). ➔ ´The strands of the original DNA molecule are separated ➔ ´Two new strands are assembled POLYMERASE CHAIN REACTION (PCR) TESTING ➔ Polymerase chain reaction (PCR) is a technique for replicating small quantities of DNA or broken pieces of DNA found at a crime scene, outside a living cell. ➔ Polymerase chain reaction is the outgrowth of knowledge gained from an understanding of how DNA strands naturally replicate within a cell ➔ For the forensic scientist, PCR offers a distinct advantage in that it can amplify minute quantities of DNA many millions of times ◆ 1.First, the DNA is heated to separate it. ◆ 1.Second, primers (short strands of DNA used to target specific regions of DNA for replication) are added, which hybridize with the strands. ◆ Third, DNA polymerase and free nucleotides (A, T, G, and C) are added to rebuild each of the separated strands ◆ Now, this cycle is repeated 25 to 30 times ● ´Within a few hours a short strand of DNA can be multiplied a billionfold. ➔ Appropriate primers are positioned close to the repeat units of a DNA segment in order to initiate the PCR process that will create short or mini STRs ➔ Using the technology of PCR, one can simultaneously extract and amplify a combination of different STRs. ➔ A triplex system containing three loci: FGA, vWA, and D3S1358, indicating a match between the questioned and the standard/reference stains. PRODUCT RULE ➔ A high degree of discrimination and even individualization can be attained by analyzing a combination of STRs (multiplexing). ➔ Because STRs occur independently of each other, the probability of biological evidence having a particular combination of STR types is determined by the product of their frequency of occurrence in a population. ➔ Hence, the greater the number of STRs characterized, the smaller the frequency of occurrence of the analyzed sample in the general population. STANDARDIZING STR TESTING ➔ Currently, U.S. crime laboratories have standardized on 13 STRs for entry into a national database (CODIS). ➔ A high degree of discrimination and even individualization can be attained by analyzing a combination of STRs (multiplexing) and determining the product of their frequencies. ➔ With STR, as little as 125 picograms of DNA is required for analysis. This is equivalent to about 18 DNA containing cells SEX DETERMINATION BY STRS ➔ The amelogenin gene, which is actually the gene for tooth pulp, is shorter by six bases in the X chromosome than in the Y chromosome ➔ Hence, when the amelogenin gene is amplified by PCR and separated by electrophoresis, males, who have an X and a Y chromosome, show two bands; females, who have two X chromosomes, have just one band. ➔ Forensic scientists can also type STRs located on the Y or male chromosome. Y-STRs prove useful when multiple males are involved in a sexual assault. For example an STR pattern arising from three males will have only three bands. Y- STRS ➔ Another tool available in the arsenal of the DNA analyst is the ability to type STRs located on the Y chromosome, which is male specific. ➔ More than 20 different Y-STR markers have been identified. ➔ Y-STRs will prove useful when multiple males are involved in a sexual assault. ➔ A Y-STR analysis will have only one band or peak, rather than the conventional STR which is derived from two chromosomes and has two bands or peaks. ➔ The Y-STR is therefore less complicated in appearance and interpretation. MITOCHONDRIAL DNA ➔ ´Another type of DNA used for individual characterization is mitochondrial DNA. ➔ Mitochondrial DNA (mtDNA) is located outside the cell’s nucleus and is inherited from the mother ➔ Mitochondria are structures found in all our cells used to provide energy that our bodies need to function MITOCHONDRIAL DNA TESTING ➔ Mitochondrial DNA typing does not approach STR analysis in its discrimination power and thus is best reserved for samples, such as hair, for which STR analysis may not be possible. ➔ Forensic analysis of mtDNA is more rigorous, time consuming, and costly when compared to nuclear DNA analysis. ➔ Also, all individuals of the same maternal lineage will be indistinguishable by mtDNA analysis. ➔ Two regions of mtDNA HV 1 and HV 2, have been found to be highly variable and a procedure known as sequencing is used to determine the order of base pairs ➔ Two regions of mtDNA HV 1 and HV 2, have been found to be highly variable and a procedure known as sequencing is used to determine the order of base pairs. ➔ Every cell in the body contains hundreds of mitochondria ➔ It provides energy to the cell ➔ Each mitochondrion contains numerous copies of DNA shaped in the form of a loop ➔ ´Distinctive differences between individuals ➔ Mitochondrial DNA makeup are found in two specific segments of the control region on the DNA loop known as HV1 and HV2 CODIS ➔ Perhaps the most significant tool to arise from DNA typing is the ability to compare DNA types recovered from crime scene evidence to those of convicted sex offenders and other convicted criminals ➔ ´CODIS (Combined DNA Index System) is a computer software program developed by the FBI that maintains local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and profiles of missing persons. It currently contains about 470,000 profiles from unsolved cases. ➔ Currently, U.S. crime laboratories have standardized on 13 STRs for entry into a national database (CODIS). COLLECTION OF DNA EVIDENCE ➔ ´Sources of DNA: ◆ ´Blood ◆ Semen ◆ Saliva ◆ Skin sells ◆ Hair ◆ Bone ➔ DNA is a powerful creator of physical evidence at crime scenes; e.g., bottles, cans, glasses, cigarettes, bite marks, and envelopes. ➔ Clothing from victim and suspect with blood evidence must be collected ➔ Dried blood is best removed from a surface by using a sterile cotton swab lightly moistened with distilled water that is air dried before being placed in a swab box, then a paper or manila envelope ➔ Standard/reference DNA specimens must also be collected with a buccal swab (swabbing the mouth and cheek). PACKING BIOLOGICAL EVIDENCE ➔ Before the collection of biological evidence begins, it is important that it be photographed and recorded on sketches ➔ Wearing disposable latex gloves while handling the evidence is required. These gloves should be changed frequently ➔ Safety considerations and avoidance of contamination also call for the wearing of face masks, a lab coat, eye protection, shoe covers, and possibly coveralls. ➔ Before the collection of biological evidence begins, it is important that it be photographed and recorded on sketches ➔ ´Clothing from the victim and suspect with blood evidence must be collected. ➔ The longer the time for complete absorption to occur, the lower will be the peak alcohol in the blood for a given number of drinks. ALCOHOL DISTRIBUTION ➔ When absorption is complete alcohol becomes uniformly distributed between all the watery portions of the body which is about two-thirds of body volume.à ➔ In decedents, if blood is not available other watery portions of the body; e.g., brain, cerebrospinal fluid, or vitreous humor, can be used to determine alcohol levels ALCOHOL ELIMINATION ➔ Elimination of alcohol throughout the body is accomplished through oxidation and excretion. ➔ Oxidation takes place almost entirely in the liver, where the enzyme alcohol dehydrogenase converts alcohol to acetic acid and then into carbon dioxide and water. ➔ About 5% of the alcohol is excreted unchanged in the breath, urine, and perspiration. ➔ Blood alcohol concentration is defined as percent weight per volume. Hence, 0.10% is equivalent to 0.10 grams per 100 milliliters of blood ➔ The elimination or “burn-off” rate of alcohol varies, but 0.015%/hr. seems to be a reasonable average. ➔ Hence, if your blood level of alcohol is 0.10%, it takes about 6.5 hours for you to come down to zero BLOOD ALCOHOL CONCENTRATION(BAC) ➔ The extent to which an individual may be under the influence of alcohol is usually determined by either measuring the quantity of alcohol present in the blood system or by measuring the alcohol content in the breath. ➔ Experimental evidence has verified that the amount of alcohol exhaled in the breath is in direct proportion to the blood concentration and is directly proportional to alcohol in the brain. ➔ The current legal measure of drunk driving in the United Stated is a blood-alcohol concentration of 0.08%, or 0.08 grams of alcohol per 100 milliliters of blood. Another way of expressing this is 80 mg/dL. ALCOHOL AND THE CIRCULATORY SYSTEM ➔ Humans have a closed circulatory system consisting of a heart, arteries, veins, and capillaries. ➔ Alcohol is absorbed from the stomach and small intestines into the bloodstream. ➔ Alcohol is carried to the liver where the process of its destruction starts ➔ Blood, carrying alcohol, moves to the heart and is pumped to the lungs ➔ Humans have a closed circulatory system consisting of a heart, arteries, veins, and capillaries ➔ In the lungs, the respiratory system bridges with the circulatory system. A rapid exchange takes place between fresh air in the lung’s alveoli sacs and spent blood in the capillaries surrounding the sacs. If alcohol is present in the blood, it participates in this exchange. ➔ Gas exchange in the lungs. Blood flows from the pulmonary artery into vessels that lie close to the walls of the alveoli sacs. Here the blood gives up its carbon dioxide and absorbs oxygen. The oxygenated blood leaves the lungs via the pulmonary vein and returns to the heart. ➔ The respiratory system. The trachea connects the nose and mouth to the bronchial tubes. The bronchial tubes divide into numerous branches that terminate in the alveoli sacs in the lungs. BREATH TESTERS ➔ The temperature at which the breath leaves the mouth is normally 34°C ➔ Breath testers operate on the fact that at 34°C, the ratio of alcohol in the blood to alcohol in alveolar breath is approximately 2,100 to 1. ➔ In other words, 1 milliliter of blood contains nearly the same amount of alcohol as 2,100 milliliters of alveolar breath. ➔ Breath testers that operate on the principle of infrared light absorption are becoming increasingly popular within the law enforcement community ➔ Many types of breath testers are designed to analyze an individual’s breath as it flows through a chamber in the breath tester and is exposed to infrared radiation ➔ It’s the degree of the interaction of the infrared light with alcohol in the breath chamber that allows the instrument to measure a blood alcohol concentration in breath. ➔ Some breath testing devices also use fuel cells which converts alcohol to an electrical current. FIELD TESTING ➔ Law enforcement officers typically use field sobriety tests to estimate a motorist’s degree of physical impairment by alcohol and whether or not an evidential test for alcohol is justified ➔ The horizontal gaze nystagmus test, walk and turn, and the one-leg stand are all considered reliable and effective psychophysical tests. ➔ A portable, handheld, roadside breath tester may be used to determine a preliminary breath-alcohol content. These testers use fuel-cell detectors and are not admissible in court proceedings as proof of intoxication. TESTING BLOOD FOR ALCOHOL CONTENT ➔ Gas chromatography offers the toxicologist the most widely used approach for determining alcohol levels in blood in forensic labs ➔ Hospital or clinical labs normally use autoanalyzers to measure alcohol content. These instruments measure the conversion of alcohol to acetaldehyde by alcohol dehydrogenase. The determination is made as a serum alcohol level ➔ Serum alcohol is normally converted to a blood alcohol concentration by dividing by the factor 1.16. Thus 250 mg/dL is equivalent to 215mg/dL of 0.215%. COLLECTION AND PRESERVATION OF BLOOD ➔ Blood must always be drawn under medically accepted conditions by a qualified individual. ➔ It is important that a nonalcoholic disinfectant such as betadine be applied before the suspect’s skin is penetrated with a sterile needle or lancet ➔ Once blood is removed from an individual, its preservation is best ensured when it is sealed in an airtight container after an anticoagulant and a preservative have been added and stored in a refrigerator ➔ Failure to properly preserve blood removed from living individuals may result in a decline of the blood alcohol level. ➔ In descendants, alcohol may be produced during decomposition creating an elevated ➔ For many drugs, blood concentration levels are readily determined and can be used to estimate the pharmacological effects of the drug on the individual ➔ The concentration of a drug in urine is a poor indicator of how extensively an individual’s behavior or state is influenced by the drug. ➔ Before drawing conclusions about drug induced behavior, the analyst must consider other factors including age, health, and tolerance. ➔ Once the drug is extracted and identified, the toxicologist may be required to provide an opinion on the drug’s effect on an individual’s natural performance or physical state. ➔ For many drugs, blood concentration levels are readily determined and can be used to estimate the pharmacological effects of the drug on the individual ➔ The concentration of a drug in urine is a poor indicator of how extensively an individual’s behavior or state is influenced by the drug. ➔ Before drawing conclusions about drug induced behavior, the analyst must consider other factors including age, health, and tolerance ➔ Often, when dealing with a living person, the toxicologist has the added benefit of knowing what a police officer may have observed about an individual’s behavior and motor skills. DETECTING DRUGS IN HAIR ➔ Drugs present in blood diffuse through the capillary walls into the base of the hair and become permanently entrapped in the hair’s hardening protein structure ➔ As the hair continues to grow, the drug’s location on the hair shaft becomes a historical marker for delineating drug intake. ➔ Given that the average human head hair grows at the rate of 1 centimeter per month, analyzing segments of hair for drug content may define the timeline for drug use ➔ The chronology of drug intake may be distorted by drugs penetrating the hair’s surface as a result of environmental exposure, or drugs may enter the hair’s surface through sweat. NON DRUG POISONS ➔ Heavy metals such as arsenic, bismuth, antimony, mercury, and thallium are only occasionally encountered because severe environmental protection regulations restrict their availability to the general public. ➔ To screen for many of these metals, the suspect body fluid is dissolved in a hydrochloric solution and a copper s strip is inserted into the solution. The presence of a silvery or dark coating on the copper indicates the presence of a heavy metal ➔ Carbon monoxide is one of the most common poisons encountered in a forensic laboratory. ➔ To measure the concentration of carbon monoxide in the blood, spectrophotometric methods determine the amount of carboxyhemoglobin relative to oxyhemoglobin or total hemoglobin; or a volume of blood can be treated with a reagent to liberate the carbon monoxide, which is then measured by gas chromatography. THE DRUG RECOGNITION EXPERT (DRE) ➔ During the 1970s, the Los Angeles Police Department developed clinical and psychophysical examinations that a trained police officer could use to identify and differentiate between types of drug impairment. ➔ This program has evolved into a national program to train police as drug recognition experts ➔ Normally, a three- to five-month training program is required to certify an officer as a drug recognition expert (DRE). ➔ The DRE program incorporates standardized methods; e.g., blood pressure, pulse, pupil size, for examining suspects to determine whether they have taken one or more drugs. ➔ To ensure that each subject has been tested in a routine fashion, each DRE must complete a standard Drug Influence Evaluation form ➔ The DRE program usually cannot determine which specific drug was ingested. ➔ Hence, it is the production of reliable data from both the DRE and the forensic toxicologist that is required to prove drug intoxication Module 7: Drugs in Forensics PSYCHOLOGICAL DEPENDENCE ➔ The common denominator that characterizes all types of repeated drug use is the creation of psychological dependence for continued use of the drug. ➔ Emotional factors that play a part in drug dependence include the personal characteristics of the user, his or her expectations about the drug experience, society’s attitudes and possible responses and the settings in which the drug is used. ➔ The intensity of the psychological experience with drugs is difficult to define. ➔ Some drugs e.g., alcohol, heroin, and cocaine with continued use lead to a high degree of involvement ➔ Others such as marijuana and codeine have a lower potential for abuse. ➔ Our general knowledge of alcohol consumption should warn us of the dangerous of generalizing when it come to drug abuse PHYSICAL DEPENDENCE ➔ Physical dependence is defined as the physiological need for a drug that has been brought about by its regular use. The desire to avoid withdrawal sickness, or abstinence syndrome, ultimately causes physical dependence or addiction ◆ Marijuana and cocaine are common drugs of abuse whose regular use does not lead to physical dependence NARCOTICS ➔ Narcotic drugs are analgesics, meaning they relieve pain by a depressing action on the central nervous system. Their depressant effects impacts on blood pressure, pulse rate and breathing rate. ➔ The regular use of a narcotic drug will invariably lead to physical dependence ➔ The most common source for these narcotic drugs is opium, extracted from poppies. ➔ Morphine is readily extracted from opium and is used to synthesize heroin ➔ Addicts frequently dissolve heroin in water by heating it in a spoon, and then inject in the skin. ➔ Heroin produces a “high” that is accompanied by drowsiness and a sense of well-being that generally last for three to four hours ➔ Codeine is also present in opium, but it is usually prepared synthetically from morphine SYNTHETIC OPIATES NOT DERIVED FROM OPIUM ➔ OxyContin, with the active ingredient oxycodone, is not derived from opium or morphine, but does have the same physiological effects on the body as do opium narcotics. ➔ OxyContin is prescribed to a million patients for treatment of chronic pain. ➔ Methadone is another well-known synthetic opiate ➔ The U.S. federal law known as the Controlled Substances Act will serve to illustrate a legal drug-classification system created to prevent and control drug abuse. ➔ This federal law establishes five schedules of classification for controlled dangerous substances on the basis of a drug’s: ◆ potential for abuse ◆ potential for physical and psychological dependence ◆ medical value SCHEDULES OF CLASSIFICATION ➔ Schedule I drugs have a high potential for abuse and have no currently accepted medical use such as heroin, marijuana, methaqualone, and LSD. ➔ Schedule II drugs have a high potential for abuse and have medical use with severe restrictions such as cocaine, PCP, and most amphetamine and barbiturate prescriptions. ➔ Schedule III drugs have less potential for abuse and a currently accepted medical use such as all barbiturate prescriptions not covered under Schedule II, such as codeine and anabolic steroids ➔ Schedule IV drugs have a low potential for abuse and have a current medical use such as darvon, phenobarbital, and some tranquilizers such as diazepam (valium) and chlordiazepoxide (librium). ➔ Schedule V drugs must show low abuse potential and have medical use such as opiate drug mixtures that contain nonnarcotic medicinal ingredients. COLLECTION AND PRESERVATION ➔ The field investigator has the responsibility of ensuring that the evidence is properly packaged and labeled for the laboratory. ➔ Generally common sense is the best guide, keeping in mind that the package must prevent the loss of the contents and/or cross-contamination. ➔ Often the original container in which the drug was seized will suffice ➔ All packages must be marked with information that is sufficient to ensure identification by the officer in the future and establish the chain of custody. DRUG IDENTIFICATION ➔ The challenge or difficulty of forensic drug identification comes in selecting analytical procedures that will ensure a specific identification of a drug. ➔ This plan, or scheme of analysis, is divided into two phases. ◆ Screening test that is nonspecific and preliminary in nature to reduce the possibilities to a manageable number ◆ confirmation test that is a single test that specifically identifies a substance PRELIMINARY ANALYSIS ➔ Faced with the prospect that the unknown substance may be any one of a thousand or more commonly encountered drugs, the analyst must employ screening tests to reduce these possibilities to a small and manageable number ➔ This objective is often accomplished by subjecting the material to a series of color tests that will produce characteristic colors for the more commonly encountered illicit drugs: ◆ Marquis Test – heroin and amphetamines ◆ Duquenois-Levine – marijuana ➔ This objective is often accomplished by subjecting the material to a series of color tests that will produce characteristic colors for the more commonly encountered illicit drugs: ◆ Scott Test – cocaine ◆ Dillie-Koppanyi – barbiturates ◆ Van Urk – LSD ➔ Microcrystalline tests can also be used to identify specific drug substances by studying the size and shape of crystals formed when the drug is mixed with specific reagents. CONFIRMATIONAL DETERMINATION ➔ Once this preliminary analysis is completed, a conformational determination is pursued ➔ Forensic chemists will employ a specific test to identify a drug substance to the exclusion of all other known chemical substances. ➔ Typically infrared spectrophotometry or gas chromatography-mass spectrometry is used to specifically identify a drug substance QUALITATIVE VS QUANTITATIVE ➔ Another consideration in selecting an analytical technique is the need for either a qualitative or a quantitative determination. ➔ The former relates just to the identity of the material, whereas the latter requires the determination of the percent composition of the components of a mixture CHROMATOGRAPHY ➔ Chromatography is a means of separating and tentatively identifying the components of a mixture ➔ The theory of chromatography is based on the observation that chemical substances have a tendency to partially escape into the surrounding environment when dissolved in a liquid or when absorbed on a solid surface. ➔ In chromatography, one phase is always made to move in one direction over a stationary or fixed phase ➔ Those materials that have a preference for the moving phase will slowly pull ahead and separate from those substances that prefer to remain in the stationary phase. GAS CHROMATOGRAPHY ➔ In GC, the moving phase is actually a gas called the carrier gas, which flows through a column ➔ The stationary phase is a thin film of liquid contained within the column. ➔ After a mixture has traversed the length of the column, it will emerge separated into its components. ➔ In this illustration of chromatography, the molecules represented by the blue balls have a greater affinity for the upper phase and hence will be pushed along at a faster rate by the moving air. Eventually, the two sets of molecules will separate from each other, completing the chromatographic process ➔ The written record of this separation is called a chromatogram ➔ The time required for a component to emerge from a GC column is known as retention time ➔ Gas chromatography permits rapid separation of complex mixtures into individual compounds and allows identification and quantitative determination of each compound. As shown, a sample is introduced by a syringe (1) into a heated injection chamber (2). A constant stream of nitrogen gas (3) flows through the injector, carrying the sample into the column (4), which contains a thin film of liquid. The sample is separated in the column, and the carrier gas and separated components emerge from the column and enter the detector (5). Signals developed by the detector activate the recorder (6), which makes a permanent record of the separation by tracing a series of peaks on the chromatograph (7). The time of elution identifies the component present, and the peak area identifies the concentration ➔ a) An unknown mixture of barbiturates is identified by comparing its retention times to (b), a known mixture of barbiturates Module 8: Biometrics and Mobile Devices Forensics WHAT IS BIOMETRICS? ➔ Access Control to accurately and efficiently identify humans ➔ Cutting Edge Technology ➔ Uses Individuals Biological and Behavioral traits BIOMETRICS: 2 MAIN FUNCTIONS ➔ Biometric matching or verification ◆ The first function is biometric matching or verification. ◆ This system is capable of identifying someone out of a crowd by scanning select biometric characteristics into a database ➔ Biometric identification ◆ The second application of biometrics relates to access control through biometric identification. ◆ Access-control systems will create and store databases of biological traits and compare them to the individual attempting to gain entry into a device or facility TYPES OF FORENSIC BIOMETRICS ➔ The majority of biometric systems can be split into 2 different groups: ◆ 1st group → physiological biometrics, which contains: fingerprints, hand, iris, retina, and facial scans ◆ 2nd group → behavioral biometrics, which is much less stable and includes: handwriting, voice, keystroke, and gait recognition BIOMETRICS: ENROLLMENT PROCESS ➔ The first process that each biometrics system must perform is known as the enrollment process ➔ The enrollment process captures a person's biometric data and stores it in a database for later use ◆ Once the information completes its runs through a data preprocessing module, feature extraction begins BIOMETRICS: EXTRACTION ➔ The extraction module is responsible for finding patterns in the traits extracted by the sensor by using mathematical equations. ➔ Every system uses different equations and algorithms to judge unique characteristics THE NEXT GENERATION SYSTEM ➔ The FBI has been integrating biometric technology into their new identification system. ➔ In 2014, The Next Generation Identification (NGI) system replaced the Integrated Automated Fingerprint Identification System. ➔ The NGI system provides a broader selection of resources and information for law enforcement agencies across the country IRIS BIOMETRICS ➔ Iris biometrics is replacing retina biometrics because it is an all around better technology and more functional for both law enforcement and business security. ➔ The goal is to create a unique template of the iris to be compared against a database in the NGI system. This template is known as an IrisCode. ➔ The FBI is currently perfecting its data repository and techniques for obtaining iris biometric data for use in the NGI system. ➔ Over 12,000 IrisCodes have been sent to the FBI, as they continue to test the capabilities that the NGI system possesses. Inside of the human eye showing iris scan showing eye with scanner and retina and optic nerve computer interface FACIAL RECOGNITION ➔ Facial recognition biometrics have a variety of different approaches available to analyze facial data. ➔ Multiple techniques are required to create a viable reconstruction and analysis of a human face. ◆ Proliferation of WI-FI networking ◆ Smart Phones evolved into tablets and ipads ➔ Drawbacks of 1G: ◆ Overlap indicated by red circles ◆ Transmitting patterns are hexagonal TYPES OF MOBILE DEVICES ➔ A cellular systems is a network of relatively short-distance transceivers that are spaced strategically so that low-power transmitters can reach the phones in their coverage areas and the very low-power transmitters in the cell phones can reach the cell ➔ Digital (2G) cellular networks moved phones into the small, handheld form ➔ Used 2 standards : ◆ GSM - Global system for mobile communications ◆ CDMA - Code division multiple access ➔ They were digital, the new network opened the door for practical data communications and the beginning of what was referred to as "feature phones.” ➔ The architectural functionality that distinguishes 2G from 3G is that 2G systems were circuit switched and 3G systems are packet switched. ➔ The advent of packet-switched mobile phone networks allowed virtually any kind of data to be accessed by the mobile device, and the smart phone was born. ➔ Native IP (4G) networks differ technologically from 3G networks in that they access the Internet directly, increasing speed and bandwidth dramatically. FORENSIC CHALLENGES: MOBILE PHONE OPERATING SYSTEMS ➔ The most popular operating systems for mobile devices—including phones and tablets— are Apple iOS, Google Android, and Microsoft Windows Phone OS ➔ The 1G devices ◆ Virtually none of these have an operating system( OS) ◆ Anything that has been deleted is no longer available ➔ The 2G devices ◆ Most have the real Oss ◆ Ability to recover deleted messages varies from phone model to model ➔ 3G and 4G phones ◆ The closest in architecture and design to a PC ◆ They behave the same way—especially 4G devices—and they have the ability to download and install applications ("apps") the same as any PC or Mac FORENSIC CHALLENGES: VARIABILITY OF MOBILE DEVICES ➔ One interesting aspect of mobile device forensics is geolocation ➔ The GPS can locate the user's activities and when used with a timeline, can place the user in the vicinity of a crime ➔ That can make it much easier to track the owner's movements ➔ Each device has its own quirks, and each device needs special connectors and special device drivers on the tool that is examining it to decipher what is on the device's storage. ➔ Device storage also takes several forms, such as ◆ onboard nonvolatile memory ◆ mini-SD cards that add storage in a modern smartphone or tablet EXTRACTING DATA FROM MOBILE DEVICES ➔ All mobile devices should be kept in a Faraday bag or box. This prevents changes from being made to the device remotely. ➔ Physical Extraction ➔ Logical Extraction ➔ Or both ➔ Physical Extraction : Physical forensic images are bit-by-bit copies of the file system, including deleted data. ➔ Logical extraction : is a snapshot of the file system showing what the file system wants the user to see. ➔ Mobile device forensic analysis can provide an overlay to physical evidence and timelines as well as computer forensic timelines to give a clearer picture of the events preceding and following a crime event. ➔ Examiners make it a practice to run the forensic image twice, taking one of the images and treating it as evidence. ➔ The examiner should decide, based on what can be done for the particular device, whether to obtain a physical or logical extraction or both. MOBILE PHONE ARCHITECTURE ➔ SD (Secure Digital) cards are storage expansion cards that many mobile devices can accept. ◆ The SD card adds memory for storing such things as photos and music. SD cards are nonvolatile. Module 9: Principles of Histology Pre-resource reading: http://www.histology.leeds.ac.uk/what-is-histology/H_and_E.php WHAT IS HISTOLOGY? ➔ Microscopic Study of the cells and tissues ➔ To understand the microscopic, 3D organization, structure and function ➔ Most important techniques for pathologists ➔ Especially useful for the diagnosis and understanding of diseases at the cellular level ➔ Important in Forensic medicine CELLS AND TISSUES IN THE BODY ➔ 4 Basic types of tissues: ◆ Epithelial ◆ Connective ◆ Muscle ◆ Nervous ➔ Each of the tissue type is composed of: ◆ Cells ◆ Extracellular ◆ Matrix ◆ Body Fluids INTRO TO HISTOLOGY ➔ Histological methods are very useful to study the microscopic detailed structure of cells and tissues ➔ Most of the cells are colorless and transparent ➔ Staining the tissue sections is an important for visualization HISTOLOGICAL TECHNIQUES ➔ Provides a visual means of microscopic examination and analysis of the morphology and analysis of cells and tissues ➔ Specific techniques are used for: ◆ Light Microscopy ◆ Electron Microscopy ➔ Light Microscopy ◆ Paraffin Techniques ◆ Frozen sections ◆ Semi-thin Sections ➔ Electron Microscopy ◆ Tissue sections are prepared using the Semi-thin section method LIGHT MICROSCOPY -- PARAFFIN TECHNIQUES ➔ Tissue isolation and Fixation ➔ Dehydration/Clearing ➔ Paraffin embedding and Sectioning ➔ Staining TISSUE ISOLATION AND FIXATION ➔ Small square tissue blocks or small whole tissue ➔ Tissue blocks put in Appropriate chemical Fixative Solution ➔ Most common fixative is 4% formaldehyde at neutral pH ➔ Fixation is needed to stop the natural process of decomposition and autolysis ➔ Fixation helps in stabilizing and preserving the microstructure of the cells and tissue DEHYDRATION AND CLEARING OF TISSUES ➔ The tissues blocks need to be dehydrated and cleared before embedding in paraffin wax ➔ Dehydration is accomplished by slowly replacing water in the sample tissue with alcohol ➔ Tissue blocks are passed through increasing alcohol concentrations starting from 30%- 100% ( Absolute alcohol) ➔ After 100% alcohol the tissue blocks are placed in the clearing agent (generally xylene) ◆ Significance of clearing agent: Xylene ◆ The clearing agent is miscible with alcohol ◆ Make the tissue samples receptive to the infiltration of embedding agent (paraffin wax) ◆ Once the tissue samples are properly dehydrated and cleared .. they are ready for embedding EMBEDDING IN PARAFFIN WAX ➔ Paraffin wax is the most common medium for embedding tissues for light microscopy ➔ The wax infiltrates in the cells and tissues thus rendering it capable of being sliced ultrathin before stating ➔ The paraffin wax is melted in the oven ( the melting point may be 50-60°C ➔ The tissue blocks are placed in the warm molten wax ➔ After embedding the tissue is cooled down to harden TISSUE SECTIONING ➔ The tissue is trimmed and mounted on aa appropriate block for cutting ➔ The process is completed with the microtome ➔ The microtome allows for the tissue to be cut from 2-50 microns ➔ The sections are mounted on the glass slides ➔ Microtome ➔ Eosin is an acidic dye which stains the cytoplasm pink ◆ Pink stain is in most of the protein in cytoplasm OTHER TYPES OF HISTOLOGICAL STAINS PAS ➔ Periodic acid –Schiff Reaction ( PAS) ◆ Schiff Reagent is a basic fuchsin ◆ PAS stains carbohydrates …a deep red ( Magenta) color ◆ PAS is used to satin: ● Glycogen …which is the intracellular storage form of carbohydrates in cells ● Collagen, Cartilage MASSON’S TRICHROME STAINING ➔ For connective tissue staining ➔ Produces 3 colors ◆ All basophilic regions such as Nuclei -- Blue ◆ Cytoplasm, muscle, erythrocytes, keratin -- Bright red ◆ Collagen -- Green or blue ALCIAN BLUE AND VAN GIESON STAINING ➔ Alcian Blue ◆ A Mucin Stain ◆ Certain types of mucin and Cartilage stains blue ➔ Van Gieson ◆ Collagen -- stained red ◆ Nuclei -- Blue ◆ Erythrocytes and Cytoplasm -- Yellow AZAN AND GIEMSA STAINING ➔ Azan ◆ Nuclei -- Bright red ◆ Collagen , Mucin -- Blue ◆ Muscle and RBC’s -- orange to red ➔ Giemsa ◆ For blood and bone marrow smears ◆ Nuclei -- Dark blue to Violet ◆ Cytoplasm -- Pale blue ◆ RBC’s -- pink TOLUIDINE AND METHYLENE BLUE