Molecular genetics - forensics

Last updated: Saturday, 27, June, 2009

MBS Online Search Page: Click here for details

Item Process
Specimen
  1. Criminal investigation: specimens (blood, semen, hair, skin from under the fingernails) obtained from the victim are matched against specimens (usually 5mL blood in EDTA) from the suspect(s).
  2. Identity and paternity testing: 5mL blood in EDTA or 1-2 drops from a capillary sample for a child.
    Specimens are collected from the index case and from purported relatives.
    Other specimens eg, saliva, plucked hair roots may be accepted by legislation in the future.
    Consult pathologist prior to organising specimen collection.

See also Paternity testing.

Method

See Molecular genetics.

Amplification by PCR with a range of DNA polymorphisms known as short tandem repeats (microsatellites) is now more commonly used than RFLPs.

Application

Identification of individuals suspected of having committed serious crime eg, rape, murder.

Establishing the identity of an otherwise unidentifiable corpse, if likely close relatives are available for testing.

Determination of paternity by confirming or refuting a biological parental relationship.

Interpretation

The results, in a forensic context, are usually expressed as a frequency of the analysed profile (specimens from the victim) in the general population and its degree of similarity or difference from the specimen collected from the suspect.

When establishing a biological relationship the results are usually expressed as a probability of paternity or exclusion of paternity.

Reference

Hochmeister MN. Molecular Aspects of Medicine 1995; 16: 315-417.