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Identification Using Blood Groups
Forensic Serology Identification Using Blood Groups This presentation contains graphic pictures. Chem-195 H 7/29/2018
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Forensic Serology Serology – term used to describe a broad range of laboratory tests using reactions of blood serum and body fluid The serology section of a forensic laboratory may deal with any or all of the following: blood typing characterization of unknown blood stain patterns for crime reconstruction paternity testing semen identification in rape cases DNA techniques used for identification 7/29/2018 Chem-195 H
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The Composition of Blood
Blood is a mixture of many components: cells inorganic substances (salts) enzymes water proteins 55 % of blood content is plasma – mostly water and substances dissolved in it Most of the solid materials (by weight) are cells red blood cells, RBCs (erythrocytes) white blood cells (leukocytes) 7/29/2018 Chem-195 H
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Forensic Characterization of Bloodstains
Three questions that must be answered by the forensic investigator: 1) Is it blood? Benzidine Test Kastle-Meyer Test Hemastix (o-tolidine, TMB) Luminol Test 2) Is it human blood? Precipitin Test 3) Can it be associated with an individual? 7/29/2018 Chem-195 H
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Luminol Red blood cells contain hemoglobin (Hb) – the protein responsible for transporting oxygen Each Hb contains four iron (Fe) containing hemes Heme structure 7/29/2018 Chem-195 H
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Luminol Red blood cells contain hemoglobin (Hb) – the protein responsible for transporting oxygen Each Hb contains four iron (Fe) containing hemes Heme structure 7/29/2018 Chem-195 H
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Precipitin Test: A serological test using a precipitin reaction to detect the presence of a specific antigen; specifically : a test used in criminology for determining the human or other source of a bloodstain. 7/29/2018 Chem-195 H
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Blood Antigens On the surface of red blood cells are chemical structures (proteins) called antigens The presence of antigens allow a living system to recognize foreign biological substances Antigens also impart specific characteristics to the red blood cells. These characteristics can be partly used to identify individuals Human red blood cells have more than 15 different antigen types that have been discovered 7/29/2018 Chem-195 H
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Blood Typing Blood typing involves determination of the antigens present on an individual’s RBCs The two most common blood typing systems used are the A-B-O method and the Rh method type A blood – contain “A” antigen on RBCs type B blood – contain “B” antigen on RBCs type AB blood – contains both A and B antigens type O blood – contain no A or B antigens Rh+ blood – contain Rh antigen Rh- blood – no Rh antigen 7/29/2018 Chem-195 H
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Blood Typing Blood also contains antibodies – proteins that recognize and bind to certain, specific antigens Blood Type Antigens on RBC Antibodies A A anti-B B B anti-A AB AB none O none both A & B 7/29/2018 Chem-195 H
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Blood Typing When blood containing a specific antigen is mixed with blood containing the corresponding antibodies, the blood clots The clots can then be removed by the host system 7/29/2018 Chem-195 H
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Blood Typing Human serum containing specific antibodies can be purchased Separately mix a drop of unknown blood sample with drop of each anti-serum Reaction between blood and anti-serum No reaction between blood and anti-serum 7/29/2018 Chem-195 H
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Blood Typing Example A sample of unknown blood is mixed with three anti-sera samples: Tube 1 (Anti-A): No reaction Tube 2 (Anti B): No reaction Tube 3 (Anti Rh): Cloudy reaction 7/29/2018 Chem-195 H
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Blood Typing Example A sample of unknown blood is mixed with three anti-sera samples: Tube 1 (Anti-A): No reaction Tube 2 (Anti B): No reaction Tube 3 (Anti Rh): Cloudy reaction In terms of the A-B-O and Rh systems, what type blood is the sample? O positive 7/29/2018 Chem-195 H
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Blood Splatter Analysis
Categories of Bloodstains: Passive (dripping) Transfer (smearing) Projected Projected Bloodstains occur in shootings, trauma from blunt weapons, hacking, or slashing attacks. 7/29/2018 Chem-195 H
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Projected Bloodstain Analysis
Two Important Determinations: a. direction of splatter b. angle of impact with surface sin = (width drop / length drop) 7/29/2018 Chem-195 H
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Bloodstains are classified into three basic types:
Passive stains, transfer stains and projected or impact stains. Passive stains include drops, flows and pools, and typically result from gravity acting on an injured body. 7/29/2018 Chem-195 H
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Transfer stains result from objects coming into contact with existing bloodstains and leaving wipes, swipes or pattern transfers behind such as a bloody shoe print or a smear from a body being dragged. Impact stains result from blood projecting through the air and are usually seen as spatter, but may also include gushes, splashes and arterial spurts. 7/29/2018 Chem-195 H
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Passive bloodstain on a wooden floorboard
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Transfer pattern made by a bloody hand.
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Back spatter from a gunshot wound on a steering wheel
Gunshot spatter - includes both forward spatter from the exit wound and back spatter from the entrance wound. Gunshot spatter will vary depending on the caliber of the gun, where the victim is struck, whether the bullet exits the body, distance between the victim and the gun and location of the victim relative to walls, floors and objects. Typically, forward spatter is a fine mist and back spatter is larger and fewer drops. 7/29/2018 Chem-195 H
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Arterial spray - refers to the spurt of blood released when a major artery is severed.
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Forensic Characterization of Saliva
Saliva is a mixture of many components: 99% water Mucin (protein helps in swallowing) Amylase (enzyme to help digest carbohydrates) Cheek cells (good for DNA) Adults produce liters of saliva/day and it is not uncommon at crime scenes (especially involving bite marks). A simple test for saliva involves mixing starch, iodine, and a sample of the presumed saliva together. Starch and iodine are a deep blue color when mixed together. The amylase breaks down starch, however, and the color fades (takes about oC). 7/29/2018 Chem-195 H
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The Evidence Analysis Cascade
Gross Visual Examination Stereomicroscopy Biological Evidence Impression Evidence Trace Evidence Pattern Analysis Scrapping Tape lift Blood, Semen, Saliva Soil/Paint/Glass Hairs Presumptive Testing Pattern Analysis Fibers Tactile Analysis Chemical Testing Enzyme Testing ALS Immuno. Chromat. Confirmatory Testing Confirmatory Testing Instrumental Analysis Microscopy Species Testing Immuno Chromat. Microcrystal Analysis Lectins Genetic Marker Testing Pattern Analysis DNA
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Forensically Speaking: What is Blood?
Complex Connective Tissue Plasma Cells Hormones Antigens White Cells Red Cells Salts Drugs Antibodies Genetic Markers Enzymes Blood Group Substances HLA Antigens Blood Group Antigens Individual Specific Antibodies DNA Isoenzymes
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Forensically Critical Information from Blood
Drugs of Abuse Prescriptions Genetic Markers Psychological Behavior Identification Disease Susceptibility Ancestry Sexing Racial Identity Individual Identity DNA Profiling Antibody Profiling
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The Electromagnetic Spectrum Using Light to Find Biological Evidence
Ultraviolet Region Short wave Long wave Visible Region Violet Blue Green Yellow Orange Red Infrared Region >700 IR
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ALS Wavelengths Applications to Finding Biological Evidence
Evidence Type MiniScope 400 settings Goggle Camera Filter Bone /CSS/515 Orange Orange Teeth Fingernails Body Fluids CSS Orange Orange Dk Surfaces UV Clear/Yellow None “ w/crust White/oblique Clear None Alternative light sources Hair untreated Blk White/oblique Clear None treated-red/bld 415/CSS Yellow/Orange Yellow/Orange Blood , Clear/Yellow None
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Choosing a Goggle Color
Color Range ALS Setting (nm) Goggle Long wave UV Clear Violet Yellow Blue/green Orange Green-red Red CSS Orange
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