Bodyfluids Semen, saliva, blood, urine, faeces and cellular material

The detection of a body fluid can be crucial evidence in crimes against the person, for example, rape, assault or murder. The identity and distribution of particular body fluids can be key to an investigation. Body fluids can be transferred to items of clothing, objects at the crime scene, another individual, weapons and may also be present on swabs taken at the crime scene or during medical examinations.

The detection and analysis of body fluids is only the start of the forensic scientist’s role. Often the most complex part of a forensic scientist’s job is interpreting the results, especially if DNA is involved. It can be extremely difficult to determine whether or not a particular DNA result can be attributed to a specific body fluid. In the case of Adam Scott that hit the headlines a couple of years ago, his DNA had been attributed to semen on a victim of rape and yet it turned out that his DNA was only present in that victim’s sample as a result of contamination of that sample in the laboratory with a sample of his saliva that had come from another case:


The mistake was discovered principally due to geography; Mr. Scott resided in Exeter but the rape with which he was charged was in Manchester.

Some laboratory tests for body fluids can be fairly insensitive and certainly are not uniquely diagnostic, for example, for saliva. There is no validated test at all in the UK for vaginal material or for menstrual blood.

With SLS Forensics’ extensive casework experience and expertise we can provide advice on body fluid evidence. Ultimately the court will want to know what the overall body fluid findings mean in relation to the prosecution and defence accounts. Often forensic statements served by the Crown do not include any defence alternative as this was perhaps not available at the time the statements were written. It is crucial for any such evidence to be used in court that the scientific findings are re-evaluated using both prosecution and defence accounts.