Species Identification (Forensic)
Definition
The determination of whether biological material originates from a human or from a specific non-human species, using species-specific antisera (precipitin test) or species-targeted molecular probes. Relevant in cases where bloodstains are claimed to be animal in origin or where wildlife crime is investigated.
- Field
- Forensic immunology, biology
- Classic method
- Precipitin test with species-specific antisera
- Modern method
- Species-targeted molecular probes
- Typical case use
- Disputing human origin of a bloodstain; wildlife crime
Common questions
How does the precipitin test actually distinguish human from animal blood?+
Antiserum raised against human blood proteins forms a visible precipitate line only when it meets human antigens, so a stain that produces no line with human antiserum but reacts with an animal antiserum is identified as non-human.
Why has DNA testing largely replaced the precipitin test in modern labs?+
Molecular probes work on smaller, more degraded samples and give a more specific result than antisera, which can cross-react between closely related species and produce a weaker or ambiguous signal.
Related terms
- Antigen-Antibody Reaction
- The specific non-covalent binding between an antigen (a molecule capable of eliciting an immune response) and the antibody produced against it. In...
- Chain of Custody
- The documented chronological record of who collected, handled, transferred, and examined a piece of evidence. For digital evidence, chain of custody includes...
- ELISA (Enzyme-Linked Immunosorbent Assay)
- A plate-based immunoassay format in which a target antigen is captured by an antibody bound to a solid surface, detected by a...
- Lateral-Flow Immunoassay
- A point-of-care competitive immunochromatographic format on a nitrocellulose strip. In the absence of drug, colloidal gold-labelled antibody is captured at a test...
- Precipitin Test
- A serological method in which an antiserum specific to one species' proteins is mixed with an extract of an unknown specimen. Formation...