Biological Evidence

Forensic Serology

A branch of forensic science that identifies and analyzes biological fluids, particularly blood, to connect suspects to crime scenes.

ABO Blood Grouping System

A system that identifies blood types based on the presence or absence of A and B antigens on red blood cells.

Type A

Blood type where red blood cells have A antigens and plasma contains anti-B antibodies.

Type B

Blood type where red blood cells contain B antigens and plasma contains anti-A antibodies.

Type AB

Blood type with both A and B antigens on red blood cells and no antibodies against A or B in plasma.

Type O

Blood type that has neither A nor B antigens and has both anti-A and anti-B antibodies in plasma.

Rh Factor

The presence or absence of the Rh antigen on red blood cells, determining if blood is Rh-positive or Rh-negative.

Agglutination Test

A method to determine blood type by mixing blood samples with antibodies and observing for clumping.

Cuticle

The outermost layer of the hair shaft, composed of overlapping keratinized cells providing structural integrity.

Cortex

The middle layer of the hair shaft containing pigment granules responsible for hair color.

Medulla

A central canal-like structure in the hair shaft, providing information on species identification.

Comparison Microscope

An instrument used in forensic science to analyze two hair samples side-by-side for morphological comparison.

Contamination of Hair Samples

The risk that hair samples may be mixed with DNA from various sources, complicating analysis.

Presumptive Test for Semen

A test, such as the Phadebas® Amylase Test, that indicates the possible presence of semen by detecting alpha-amylase.

Confirmative Test for Semen

Tests like the Christmas Tree Stain and microscopic examination that confirm the presence of sperm cells.

Kastle-Meyer Test

A presumptive test for blood that detects hemoglobin, resulting in a pink color if blood is present.

Takayama Test

A confirmative blood test that detects hemoglobin crystals, providing definitive confirmation of blood.

Blood Evidence Collection

Methods such as swabbing, absorbent material, and scraping to gather blood samples from crime scenes.

Presumptive Test for Blood

A test used to indicate the possible presence of blood, often based on color changes, such as in the Kastle-Meyer Test.

Phadebas® Amylase Test

A presumptive test for semen that detects the enzyme alpha-amylase, indicating the potential presence of semen.

HemaStix Test

A presumptive test for blood using strips that change color upon contact with hemoglobin.

Luminol Test

A presumptive test for blood that produces a luminescent reaction in the presence of hemoglobin, even in diluted samples.

Semen Detection Tests

Various tests utilized to indicate the presence of semen, including enzyme and colorimetric assays.

Saliva Detection Tests

Tests designed to indicate the presence of saliva, often utilizing enzyme detection methods like the Phadebas® Amylase Test.

Limitations of Presumptive Tests

These tests indicate the potential presence of substances but cannot confirm identity; further confirmatory testing is needed.