forensic

Class Characteristics

Traits shared by a group of objects or persons.

Individual Characteristics

Features unique to a single object/person.

DNA Base Pairs

The building blocks of DNA: A-T (Adenine–Thymine) and G-C (Guanine–Cytosine).

Short Tandem Repeats (STRs)

Repeating DNA sequences (2–6 base pairs long) used in DNA profiling.

CODIS

Combined DNA Index System – a national DNA database used by law enforcement.

PCR Analysis

Polymerase Chain Reaction – a method to copy tiny amounts of DNA into millions of copies.

Gel Electrophoresis

A lab technique to separate DNA fragments by size using an electric current.

Sources of DNA

Blood, saliva, semen, skin cells, hair roots, sweat, etc. Any biological material containing cells.

Forensic Serology

The study of bodily fluids in relation to crime scenes.

Luminol Test

A chemical test that reacts with iron in blood, producing a blue glow.

Kastle-Meyer Test

A presumptive test for blood using phenolphthalein and hydrogen peroxide.

Precipitin Test

Determines if a blood sample is human or from another species using antibodies.

ELISA Test

Enzyme-Linked Immunosorbent Assay – detects the presence of antigens or antibodies.

Acid Phosphatase Test

Presumptive test for semen, enzyme is found in high concentrations in seminal fluid.

Cuticle

Outer layer of a hair strand made of overlapping scales.

Cortex

The middle part of the hair shaft; contains pigment and structure.

Medulla

The innermost layer of hair; may be continuous, fragmented, or absent.

Follicle

The part of the skin from which the hair grows; can contain nuclear DNA.

Follicular Tag/Root

Tissue attached to the root of a pulled hair; rich source of DNA.

Blood Types

A, B, AB, and O based on the presence or absence of A and B antigens.

Blood Antigens

Proteins found on the surface of red blood cells that determine blood type.

Blood Antibodies

Proteins in plasma that attack foreign antigens.

Agglutination

Clumping of red blood cells due to reaction between antigens and antibodies.

Basic Blood Spatter Measurements

Include angle of impact, height of fall, and diameter of spatter.

Relationship of Blood Spatter to Weapon Velocity

Describes the size of blood drops based on the velocity of the weapon.