Body Fluids and DNA

In any case involving body fluids and DNA, it is crucial that an appropriate strategy for targeting, locating, identifying and analysing the relevant materials is utilised.  In a sexual assault, this will usually be primarily a search for semen, but depending on the alleged circumstances identification of other body fluids may also be relevant -  for example saliva, faeces or vaginal secretions.  In a violent assault, the focus may be on the transfer of blood and analysis of any patterns within the blood. In some cases, the detection of DNA transferred by touch will be important.

Following the laboratory examination, the forensic scientist makes an interpretation of the scientific findings in the context of the case circumstances – taking into account the presence or absence of specific body fluids and DNA, together with the amounts, location and any patterns of the materials transferred.  In order to best assist the court, the scientific findings need to be evaluated against both the prosecution and defence accounts, in order to provide an assessment of the weight of the evidence. 


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Forensic services in body fluids and DNA

The PFS team of forensic biologists have a vast experience of dealing with cases involving body fluids and DNA and we offer the following services:

  • Case review and expert witness services
  • Review of whether an appropriate strategy for the examination of the case items has been utilised
  • Review of the execution of the body fluid searches and tests
  • Advice on the most suitable DNA test to attempt based on the case circumstances
  • Review of the DNA findings and match statistics
  • Review of DNA mixture interpretation
  • Review and advice on suitable propositions for DNA calculations
  • Review of whether the DNA detected can be attributed to a specific body fluid
  • Review of the transfer and persistence of body fluids and DNA
  • Review of historic cases
  • The drawing together of the body fluid findings and the DNA results
  • Interpretation and evaluation of the findings within the context of the case information and the prosecution and defence accounts

PFS do not have facilities for DNA analysis and do not offer DNA testing for either criminal or civil cases. If this is required then we can advise on suitable DNA tests and on accredited laboratories that can provide such analysis.