Serology

Serology

The study of bodily fluids and their components for forensic analysis.

Presumptive testing

A screening test done to determine if a fluid is blood or semen, based on a visible color change when a potential component of the fluid is present.

Kastle-Meyer (KM)

A presumptive test for blood that involves adding KM reagent to stain the sample, followed by the addition of 3% H2O2. A pink color change indicates a positive result.

Acid Phosphatase (AP)

An enzyme secreted into seminal fluid that can be used as a presumptive test for semen. A purple color change indicates the presence of acid phosphatase enzyme.

Confirmatory testing

Tests performed after a presumptive test gives a positive result to verify the presence of a specific fluid.

Takayama crystal test for blood

A confirmatory test for blood that involves microscopic examination of crystalline structures.

RSID Blood Test

A confirmatory test for blood that uses a rapid stain identification method.

Microscopic Sperm searches

A confirmatory test for semen that involves microscopic examination for the presence of spermatozoa.

Blood Typing

The classification of blood based on the presence or absence of specific antigens on red blood cells.

Plasma

The fluid portion of blood that makes up 55% of its volume and contains water, antibodies, vitamins/minerals, and proteins.

Blood Typing

The classification of blood based on the presence or absence of specific antigens on red blood cells.

Presumptive Testing

Screening tests used to determine if a fluid is blood or semen, such as the Kastle-Meyer Test and Luminol test.

Confirmatory Testing

Tests performed after a presumptive test gives a positive result to verify the presence of a specific fluid, such as the Takayama crystal test for blood and RSID Blood Test for semen.

Semen

The fluid ejaculated from the male reproductive system that contains spermatozoa, sugars, proteins, inorganic ions, and buffering agents.

Acid Phosphatase Test

A presumptive test for semen that detects the presence of acid phosphatase enzyme, which is found in high concentrations in semen.

Christmas Tree Staining

A confirmatory test for semen that uses red and green stains to visualize DNA and cytoplasm.

RSID (Rapid Stain Identification)

A confirmatory test for semen that detects the presence of semenogelin, a glycoprotein abundant in semen.

Sexual Assault Evidence

Various samples collected from a sexual assault investigation, including pubic combings, genital swabs, and clothing.

Saliva

The fluid produced by the salivary glands that contains water, electrolytes, mucus, white blood cells, epithelial cells, and enzymes.

Starch-iodine assays

Presumptive tests for the presence of amylase enzyme in saliva, which causes a color change in the presence of starch.

RSID for saliva

A confirmatory test for saliva that detects the presence of specific proteins using monoclonal antibodies.

Urease Test

A presumptive test for urine that detects the presence of urea by turning filter paper blue.

DNA

Genetic material found in almost all cells that can be used for individual identification through DNA profiling.

Short Tandem Repeats (STRs)

Small regions along the DNA chain where a sequence is repeated consecutively, used for DNA profiling.

Contamination

The introduction of foreign material to a crime scene or evidence, which can occur at any step of the forensic process.

Direct transfer

Transferring cells and DNA to an object or surface through direct contact or touching.

Indirect transfer

DNA found on an item without having directly touched it.

Cross contamination

Transfer of material from one item of evidence to another, often due to improper handling or packaging.

Role of Forensic Biologist

To examine physical evidence for the presence of biological fluids or skin cells, identify the fluid, generate DNA profiles, and associate the evidence with known individuals or other cases.

Sample Flow

The process of examining, extracting, quantifying, amplifying, separating, and analyzing DNA samples in a forensic laboratory.

CODIS

Combined DNA Index System, a database that allows for the comparison of DNA profiles from crime scenes, convicted offenders, and missing persons.

STR

Short Tandem Repeat, a type of DNA analysis that examines specific regions of DNA for variations in the number of repeated sequences.

Contamination

The introduction of foreign material to a crime scene or evidence, which can occur at any step of the forensic process.

Mechanisms of transfer

Direct transfer, aerosol transfer