Collection and Preservation of Biological Evidence (Module 3)

Vocabulary flashcards covering key terms from the lecture on collection, preservation, and analysis of biological evidence.

Biological evidence

Evidence derived from living organisms, such as hair, tissue, bones, teeth, blood, semen, or other bodily fluids.

Physical evidence

Any object that plays a role in a criminal investigation and can be presented to prove facts.

DNA

The genetic material found in the nucleus and mitochondria of cells; used for identity testing.

Forensic DNA analysis

Laboratory process used to determine the genetic identity of individuals from biological evidence.

Nucleus

The organelle that houses DNA in most cells.

Mitochondria

Organelles containing a small amount of DNA, inherited maternally.

Context (crime scene)

The specific circumstances and environment of a crime scene that influence investigation.

Conclusive test

A test that definitively identifies a particular body fluid (e.g., blood or semen).

Presumptive test

A screening test that indicates the possible presence of a body fluid (e.g., saliva, urine, feces).

Body fluid

Liquid biological material such as blood, semen, saliva, urine, or feces.

Double swab technique

Using two sterile swabs with purified water, treated as one sample, often for blood collection.

Sterile swab

A swab free from contaminants to prevent DNA contamination.

Purified water

Water free from DNA contamination used for swabbing.

One sample; one set of swabs

Practice to prevent cross-contamination by using one sample with a corresponding swab set.

Common sources of biological evidence

Examples include cigarette butts, chewing gum, hair, blood, and similar items.

Cuttings from clothing

Samples taken from fabric to obtain DNA.

Subsampling

Taking smaller portions from a tissue sample for analysis.

Hair collection

Methods for obtaining hair samples for DNA analysis.

1.5 mL tube

Standard collection tube used to store biological samples.

Chain of custody

Documented, unbroken transfer of evidence through collection, preservation, and analysis.

Tamper-proof tape

Seal used to secure evidence packaging and prevent tampering.

Breathable container

Packaging that allows moisture exchange while preserving evidence.

Dry and cold storage

Storage condition to preserve DNA integrity; typically dry and refrigerated.

4°C storage

Refrigerator storage for evidence to be analyzed soon (1–2 weeks).

-20°C storage

Freezer storage for evidence analyzed within months to a year.

-80°C storage

Ultra-cold storage for long-term preservation.

UV light degradation

Exposure to UV light can degrade DNA.

DNA degradation factors

Environmental factors such as moisture, heat, and bacteria that break down DNA.

Relevant DNA evidence

DNA information that would assist the investigation.

Forensic tests available

Tests used to analyze DNA or other evidence, including tests beyond your lab.