Sexual Offences

Unravelling the complexities of the scientific evidence within the context of sexual offence cases is our area of particular expertise. Having worked in specialist sexual offences forensic teams for many years, we have extensive in depth practical and court experience from examining hundreds of this type of case, and we have held leading roles in setting standards for sexual offence examinations and their interpretation.


Evaluation and Interpretation

The evaluation and interpretation of scientific evidence in sexual offence cases can be complex and extremely challenging:

  • Forensic findings may include a range of different traces including body fluids, DNA, damage, hair and fibre transfers.
  • There can be a transfer of multiple body fluids across a number of different sexual acts.
  • DNA profiling results are often mixtures which require a high level of expertise to interpret.

Because of the nature of sexual offences, the case presented to the court is very often confined to just one person’s word against another. The issue of consent may be key and the forensic findings may appear not to assist where they merely confirm that the alleged sexual act occurred which is not in dispute.

However, the devil is in the detail. Disputed versions of events can sometimes differ in only minor ways – a focus on these differences and a meticulous consideration of the forensic findings may assist in determining whether the scientific evidence supports one account over the other.


Further Information

Our case studies  include some examples of our work in this area. Some of the questions that we are often asked regarding the evidence in sexual offences are included on our FAQ page.

Posts on our News and Views page consider some of the issues in more depth:

  • How experts can provide comment on the timeframe in which sexual intercourse may have occurred.
  • The effect of washing a semen stained item.
  • DNA transfer to the male genital region and underwear through non-intimate contact.
  • The use of Y-STR profiling to demonstrate that penetration has occurred when no semen is found.
  • Consideration of whether a DNA profile can be reliably ‘attributed‘ to semen.
  • Is the presence of semen due to a sexual offence or an innocent transfer of semen?
  • Examining damage to clothing.


Our Expertise in Sexual Offences

We have unparalled expertise in this type of case, so can provide you with reliable and high quality advice.

Our expert Julie Allard is widely published on the forensic aspects of sexual offences.  Her publications include:

DNA transfer through non-intimate social contact. Science & Justice 2016.
Optimisation of choline testing using Florence iodine reagent, including comparative sensitivity and specificity with PSA and AP tests. Science & Justice 2013.
The relevance of body fluids in the investigation of sexual offences. Chapter in Handbook of Forensic Sciences 2009.
A comparison of methods used in the UK and Ireland for the extraction and detection of semen on swabs and cloth samples. Science & Justice 2007.
The collection of data from findings in cases of sexual assault and the significance of spermatozoa on vaginal, anal, and oral swabs. Science & Justice 1997.

To instruct us or discuss the issues in your sexual offence case call or email for direct contact with one of our experts.