Body Fluids - Saliva

The detection and analysis of saliva can be used in many different types of criminal cases, from a simple spitting case, to burglaries (balaclava found at a scene, for example) to the more serious cases of sexual assault, rape and murder.

Saliva can contain a high level of amylase activity. However, this same substance can also be present, but in much lower levels, in other body fluids such as semen and vaginal material. High levels of amylase can also be detected in faeces. Of course, saliva contains DNA and any traces of saliva can be put through DNA profiling techniques.

Forensic Scientists are interested in detecting saliva in a number of different types of cases including, for example:

• where a mask or balaclava may have been used as a disguise;
• in sexual assaults where kissing/licking may have occurred;
• cases involving items such as stamps/envelopes, cigarette ends and drinks bottles.

Our forensic scientists are highly trained in the detection of saliva using chemical tests, microscopy and DNA interpretation.

In the defence context, we can, for example:

• re-examine exhibits previously examined by the prosecution, looking for traces of saliva not previously found and to ensure that there has been no other evidence type missed. There may be traces of DNA from other persons, other than the accused, that has not been found previously;
  
  
• examine the interpretations made by the prosecution and test the hypotheses produced. Is there an alternative and realistic scenario of how saliva was transferred to the item?
  
  
• check that the procedure used to examine and search the exhibits and any subsequent DNA profiling were in compliance with the laboratory’s stated, quality management procedures;
  
  
• check to see if there has been any chance of contamination of the items. DNA profiling and the detection of saliva are very sensitive techniques;
  
  
• discuss the interpretation of the results with the prosecution scientist, exploring weaknesses and strengths of the interpretation;
  
  
• check and assess the credibility of the prosecution's forensic biologist and DNA profilers;
  
  
• look for and explore realistic and viable alternatives to the interpretation of evidence and the translation of that into how/when the event occurred and how any detected body fluids were produced;
  
  
• produce a detailed report of the findings including photographs and diagrams where appropriate.

At Forensic Access we are proud of our forensic scientists, with some of the leading forensic biologists in the UK working for us. See our list of experienced forensic scientists.

Contact Forensic Access to see how we can assist you with your case work.