Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
As a forensic scientist: What forms of evidence can blood provide? As a forensic scientist: What forms of evidence can blood provide? DNA Blood type Blood trails, movements Tool marks Toxicological Reports Splatter marks Directional analysis Position of: victim, assailant, weapon Chapter 12 Forensic Serology Serology The study of antigenantibody reactions. History of Blood!!! With early Transfusions Coagulation=instant death 1901, Karl Landsteiner introduced the typing of blood, the A-B-O system 1937, Rh Factor was introduced Over 100 factors actually must be considered when performing a transfusion Structure of Blood: 1. 2. Plasma, mostly water Cells Erythrocytes: (RBC) Leukocytes: (WBC) Platelets Common Materials found in the blood: respiratory gases(O2, Co2) Bicarbonate Ions nutrients (amino acids, Monosaccharides enzymes hormones wastes, toxins Blood Typing Activity Relative Frequency of Blood Types in Human Populations Major components of Blood, Plasma: Straw colored liquid consisting mainly (90%) of water and (7%) dissolved proteins. Can be found outside of the circulatory system. Also transports: 1. 2. 3. 4. 5. 6. Proteins: (albumin, globulins, fibrinogen) Salts, Glucose Amino acids Fatty acids, Vitamins, Hormones, Cellular wastes Antigens and Antibodies Antigens: protein based structures found on erythrocytes. Used by the body to recognize cells as “Self” or “NON-self” cells Antigens can be ANY substance that stimulates the body to produce antibodies against it. Antigens and Antibodies Antibodies: a protein that destroys os inactivates a specific antigen. Found in blood serum/plasma ANTISERUM: blood serum in which there are specific antibodies Agglutination: clumping together fo rbc by the action of antibodies Antigens and Antibodies Antigens and Antibodies Toxicology Based on the antibody-antigen interaction, toxins in the blood can be identified That is how blood type was determined in our activity Blood Alcohol Determinations Using the list of observable signs of intoxication Identify this individuals level of intoxication. ImmunoAssay techniques assay - a quantitative or qualitative test of a substance (especially an ore or a drug) to determine its components; frequently used to test for the presence or concentration of infectious agents or antibodies etc. Immunoassay techniques Looking for Drugs, toxins, antibodies Antibodies not found in humans are synthesized Usually inject compound with drug (that you are testing for) into an animal Why???? Animal makes antibodies because it is a foreign substance Immunoassay techniques Enzyme Multiplied Immunoassay Technique (EMIT): Detection of drugs through a antigen-antibody reaction. SO DETECTION occurs with any other related forms of that drug type!!! Immunoassay techniques ~~EMIT screening Add subjects urine antibodies to detect material. For methadone: add methadone antibodies to the urine. [Conc] of antibodies not used indicates concentration used by the drug providing a related methadone concentration Immunoassay techniques, ~~EMIT screening Marijuana's major active agent THC Tetrahydrocannabinol (3- 4.5%) Liquid Hashish oil 8-22 % THC Metabolized into THC-9-carboxlic acid Is detectable THC-9 in smokers urine is<1 mg (millionth of a gram) 2-5 days…10 days (sometimes) Characterization of blood stain 1. When found at a CS, must determine 2. 3. 4. 5. If it really is blood Species? How closely it can be associated with a specific individual Phenolphthalein: ? Hemastix ®: ? Luminol Reagent: ? Precipitin Test: ? Characterization of blood stain 1. Phenolphthalein is used to determine presence of blood 2. Binds to peroxidase-like activity of hemoglobin. Kastle-Meyer color test When blood, phenolphthalein and peroxide added together a deep color will appear. Characterization of blood stain 3. Hemastix ® is a dipstick for blood Moisten with distilled water and dipped into the sample Positive presence of blood detected if stick turns green Characterization of blood stain 4. Luminol Reagent: Tests for by production of light rather than color. Extremely sensitive and can detect minute amounts of blood DOES NOT interfere with subsequent DNA analysis Characterization of blood stain Precipitin Test: Human Antiserum determines if blood is from animal or human origin. HOW does it work? Remember ANTIGEN-Antibody Reaction??????? 4. Characterization of blood stain 5. Precipitin Tests: (10-15 years) Serum for the precipitin test is obtained from rabbits which have produced antibodies to destroy a small quantity of human blood injected into them. A drop of this anti-human serum is added to suspect blood, which will precipitate its protein if it is of human origin. Electrophoretic method: ?? Western blotting test... analysis can detect one protein in a mixture of any number of ... Western blotting tells you how much protein has accumulated in cells Characterization of blood stain 5. Precipitin Tests: Antigen - Antibody + Characterization of blood stain Blood Splatter Lab A: Vertical Drip Pattern Blood Splatter Lab Blood Splatter Lab Categories of Bloodstains TRANSFER PASSIVE PROJECTED http://www.bloodspatter.com/BPATutorial.htm IMPACT ANGLE DETERMINATION ANGLE of IMPACT is the acute angle formed between the direction of the blood drop and the plane of the surface it strikes Forensic characterization of semen Acid phosphatase color test done to determine presence of semen Based on prostate gland secreting acid phosphate Use of a microscope at magnification of 400X provides ideal evidence if spermatozoa are found Done by immersing stain on garment into water and then placing onto slide Forensic characterization of semen cont. Many people now have vasectomies or low sperm counts Problem solved by presence of p30 protein in semen fluid Antibodies to this protein made by injecting in to other animals Antiserum then added to suspected semen stain Collection of Rape Evidence Bruises and injuries usually indicate a rape Forceful contact usually leaves a lot of evidence behind Hairs, semen, fiber, etc… All outer garments form both parties should be carefully removed over a large paper to catch any fallen debris Place where rape occurred should be sent to lab or cut out piece if too big to send to lab Collection of Rape Evidence cont. Victim should be given a physical examination as soon as possible Pubic combings Vaginal, rectal and oral swabs should be taken Allow swab to air dry before packaging Place another 2 smears directly on a slide Pulled head hairs Need 15-30 Need 50 hairs from various scalp regions Blood sample Fingernail scrapings All clothing sent to lab