identification using bodily fluids
DESCRIPTION
Forensic Serology Serology – term used to describe a broad range of laboratory tests using reactions of blood serum and body fluidTRANSCRIPT
Identification Using Bodily Fluids
Forensic Serology Identification Using Bodily Fluids STEM Forensic
Serology Serology term used to describe a broad range of laboratory
tests using reactions of blood serum and body fluid Forensic
Serology characterization of unknown blood
The serology section of a forensic laboratory deals with the
following: blood typing characterization of unknown blood stain
patterns for crime reconstruction paternity testing DNA
identification techniques The Composition of Blood
Blood is a mixture of many components: cells inorganic substances
(salts) enzymes water proteins The Composition of Blood
55 % of blood content is plasma mostly water and substances
dissolved in it Most of the solid materials are cells - red blood
cells, RBCs (erythrocytes) - white blood cells, WBCs (leukocytes)
Blood Physical Characteristics
Adult contains 5-6L - Adult contains 4-5L Temp is about 100.4 F
higher or lower than normal body T? 5 times as viscous as water
more or less resistant to flow than water? what accounts for its
viscosity? pH ranges from 7.35 7.45 (slightly alkaline) Color
ranges from scarlet (oxygenated blood) to a deep red (deoxygenated
blood). 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? Luminol Luminol
reacts with iron and becomes visible under UV light
Red blood cells contain hemoglobin (Hb) for transporting oxygen,
which is made of iron Luminol reacts with iron and becomes visible
under UV light Luminol Luminol Blood Antigens On the surface of red
blood cells are chemical structures (proteins) called antigens
Antigens allow a living system to recognize foreign substances
Antigens also have characteristics and can be used to identify
individuals Human red blood cells have more than 15 different
antigen types, but well focus on two Blood Typing Blood typing
involves determination of the antigens present on an individuals
RBCs Blood Typing The two most common blood typing systems are the
A-B-O and the Rh methods type A blood contain A antigen on RBCs
type B blood contain B antigen on RBCs type AB blood contains A
& B antigens type O blood contain no A or B antigens Rh+ blood
contains Rh antigen Rh- blood no Rh antigen Blood Typing When blood
encounters free oxygen (like in a cut), the blood clots, or
agglutinates The clots can then be removed by the host system 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 Blood Stain Patterns Dexter Blood
Stain Pattern Video Clip Catching Killers - Blood Stains 101 -Video
Clip Blood Stain Pattern Analysis
Categories of Bloodstains: Passive (dripping) Transfer (smearing)
Projected Projected Bloodstains occur in shootings, trauma from
blunt weapons, hacking, or slashing attacks. Projected Bloodstain
Analysis
Two Important Determinations: a. direction of spatter b. angle of
impact with surface sin = (width drop / length drop) Forensic
Characterization of Saliva
Saliva is a mixture of many components: 99% water Mucin (protein
helps in swallowing) Amylase (enzyme to digest carbos) Cheek cells
(good for DNA) Adults produce liters of saliva/day and it is not
uncommon at crime scenes (especially involving bite marks).
Forensic Characterization of Saliva
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).