Collecting Blood Stains at the Crime Scene
	© R.C.M.P./G.R.C.

Biological materials such as blood, body fluids and hair are identified and compared using forensic DNA analysis, microscopic analysis and biochemical methods.

Services provided by the Biological Section of a forensic science laboratory include :

• identification of biological materials;
• forensic DNA analysis;
• macroscopic and microscopic hair comparisons.

The most prominent application of DNA typing has been in identifying perpetrators of violent crime by comparison of biological samples of suspects against biological specimens that perpetrators have directly left at or taken from crime scenes (e.g. semen, saliva, skin, or blood).

DNA typing, however, is useful not only in cases where the victim cannot identify the perpetrator. Since most violent crime occurs between people who are acquainted or related, it can corroborate claims of, for example, sexual abuse where there is immediate disclosure (e.g. semen in victim's vagina). In cases where the victim is pregnant or has given birth, the foetal or child's DNA profile can be compared to the mother's and the suspect's to determine paternity. Interpretations of this sort are possible because DNA is inherited both maternally and paternally. In this way victims may be identified from the analysis of DNA in partially recovered remains or information provided on missing persons from the analysis of trace smears and "reverse paternity" interpretation.

DNA in the Human Body © R.C.M.P./G.R.C.

PCR Analysis © F.B.I. Laboratory Digest