Blood and Other Bodily fluids Looking at blood Forensics and Blood Paternity Other Bodily fluids

Who studies blood? Serologists!! Bloods parts: Leucocytes - WBC’s Erythrocytes - RBC’s Platelets – cells involved in clotting Serum – yellowish liquid that remains after clot is removed Contains most of the proteins and enzymes of the plasma

Looking at Blood – ABO system RBC’s contain antigens – determine blood type Antigens can be A or B People with type A blood have A antigens People with type B blood have B antigens People with type AB blood have A and B antigens People with type O blood do not have antigens

Rhesus Rh factor- another antigen in blood Sometimes called the D factor If present in your blood then blood type is Rh Positive If not present blood type is Rh negative So if a person has A positive blood what is in it?

Antibodies and Blood Type Serum contains specialized proteins called antibodies For every antigen there is a corresponding antibody Antibodies are specific so they only react with one type of antigen When the two combine they for a antigen-antibody complex This is how we figure out blood type

Antigen-Antibody Chart

Identifying the Stain: 3 main questions must be asked: Is it blood? Is it human? Whose blood is it? To answer these questions one must have a sample in good enough condition Putrefaction – the degrading of blood samples due to bacterial growth Bacteria like warm wet environment Dry samples are better to work with because they are less likely to be damaged

IS IT BLOOD? Testing the Stain 2 types of tests: Presumptive Cheaper and faster Tell us that blood is likely present but not a fact Used to rule out stains so we don’t waste time and money on testing a stain that is not actually blood Confirmatory Much more expensive and time consuming Tell us beyond a doubt that blood is present Only used once presumptive tests prove there is blood present

Presumptive Tests Kastle-Meyer Color Test Tetramethylbenzidine (TMB) Uses phenolphthalein and hydrogen peroxide to see if blood is present Phenolphthalein will turn dark pink in presence of blood Tetramethylbenzidine (TMB) Blood sample is lifted on a moisten cotton tip and applied to a Hemastix strip which contains TMB, if the strip turns blue-green then blood may be present Leucomalachite green (LMG) Substance that produces a green color when blood is present

Presumptive Tests that Glow Luminol – fluoresces with presence of blood Extremely sensitive can reveal blood that is 1 part per 10 million or less Can expose blood on surfaces and fabrics even after being washed, cleaned or painted over Can not detect after cleaning with bleach Does not hinder DNA analysis Fluorescein – fluoresces with presence of blood Does not react with bleach Thicker than luminol so it does not drip as much and remains on area for longer

Confirmatory Tests Most common: Teichmann and Takayama Both rely on reaction between chemicals and hemoglobin Results in the formation of crystals which can be viewed under the microscope Work well with older stains

IS IT HUMAN? Use similar tests as ABO systems An antiserum must be used Substance that contains antibodies against a specific antigen Specific antigen is human so a reaction tells you its human blood

How is antiserum created? Injection of human antigen(human blood) into an animal and allowing it to produce sufficient antibodies against the antigen The animals blood is then rich in antihuman antibodies making it the antiserum When mixed with unknown blood from crime scene it will react: If human it produces a line where they mix If not human not reaction occurs

WHO’S BLOOD IS IT? ABO system is used to find blood type Agglutination - clumping of blood, which tells you what type it is Blood must be liquid and RBC’s intact What if the blood is a stain/dried? Absorption-elution process is used A 4 step process to extract the remaining antigens

Absorption-elution Process The bloodstained material is treated with blood antiserums The antibodies in the antiserum combine with the antigens The material is washed Removes any excess antiserum-containing antibodies The sample undergoes elution Elution - process that breaks down antigen-antibody bonds by heating and washes off the unneeded antibodies The eluted antibodies then are tested against known blood antigens, and their reactions are observed Antigens and antibodies react which reveal which antigens are present in the original unknown sample

Narrowing it down further! Blood Type Population % with Blood Type O 43% A B 12% AB 3% Use of PGM An enzyme that appears in many different forms 10 common forms Can be used to narrow a suspect down from more than just blood type

Other Bodily Fluids Semen, saliva, and vaginal fluid Sexual assaults commonly leave these types of evidence Can be found on ground, clothing, victim’s body or even a envelope or stamp These fluids glow in UV light Must be careful in collection because putrefaction can occur

Semen A dead victim will be searched for evidence A live victim will undergo a rap exam at the hospital done through the use of a rape kit Presumptive and Confirmatory tests are done

Presumptive Tests Semen contains high levels of AP called SAP Acid phosphatase enzymes (AP) Class of proteins that are common in nature and are found in many animals and plants Semen contains high levels of AP called SAP If SAP is present tells us that semen is present Unfortunately vaginal fluid, certain plants – watermelon, cauliflower, some fungi, and contraceptive creams can cause a false positive Also test for spermine and choline Positive when crystals form when exposed to chemicals

Confirmatory Tests Microscopic exam Prostate-specific antigen (PSA) If spermatozoa are present it’s semen Can be intact or fragments Prostate-specific antigen (PSA) A highly concentrated antigen found in semen If no sperm are present then test for PSA Use an antigen-antibody reaction – quick and easy Vasectomy eliminates sperm release but does not effect PSA because PSA is made in the prostate! So there is still evidence available!!

Saliva This test looks for presence of amylase the enzyme present in saliva Its not confirmatory but can be found on many surfaces even a stamp or envelope Sometimes epithelial cells are present in saliva and can be tested for DNA analysis

Vaginal Fluid Difficult to detect but can be used when semen is not available or a weapon is in question Tests look for presence of glycogen containing epithelial cells found only in the vaginal canal Periodic Acid-Schiff (PAS) Chemical that when in contact with glycogen containing cells turns magenta color Problems Glycogen containing cells are only present in mature women who are of childbearing age Not all cells contain glycogen