DNA evidence has become an increasingly important tool in sexual offence cases: both in prosecuting offenders, and defending those who have been falsely accused.
The role of DNA in an investigation can vary, considering the nature of the allegation that has been made. Although DNA can be used to prove that sexual activity took place, it cannot usually demonstrate whether this activity was consensual or not, and will instead be used by police to ascertain the plausibility of the allegation and the account of the accused.
Under the Police and Criminal Evidence Act 1984, suspects must submit a sample of their DNA at the request of the police, provided that this request is made under ‘reasonable grounds’ and is considered pertinent to the investigation. This is limited to suspects who have been placed under arrest or charged; refusal to submit DNA if arrested or charged is a separate criminal offence, and police have the power to use force in obtaining a sample, on the authorisation of a senior officer.
If a suspect has not been arrested, then they may choose to voluntarily submit their DNA, but should always seek the advice of a qualified and specialised solicitor before they do so.
In the event that the case is dropped, or that the defendant is found not guilty at trial, DNA evidence may be destroyed on an application to the police, unless the case or suspect has a specific, extraordinary association with national security. If a defendant is convicted, then this evidence will usually be retained, and may be deployed in future investigations.
DNA evidence has played an important part in several high-profile criminal investigations, including investigations of sexual offences. In 1988, the first use of DNA evidence by police was in the investigation and conviction of serial sexual offender Colin Pitchfork for the rape and murder of two teenage girls. Pitchfork was apprehended by police after submitting false samples during a voluntary collection of DNA from local men. In 2008, Mark Dixie was convicted of the rape and murder of Sally Anne Brownan, when DNA evidence retained by police from a prior conviction was matched with samples found at the crime scene. And John Worboys, the prolific ‘Black Cab Rapist’, was convicted in 2009 when DNA evidence was used by prosecutors to corroborate physical symptoms of sexual assault reported by victims, who had no recollection of their attacks.
DNA has also played a significant role in exonerating suspects accused of serious crimes. Three defendants, including Raphael Rowe, were released from prison in 2000 after their conviction in 1988 for theft and murder, when their DNA was proven not to match samples found at the scene of the crime. In the United States, high-profile exonerations for sexual-related convictions on the basis of DNA have included Gary Dotson in 1989, and Kirk Bloodsworth in 1993.
Like all evidence, DNA must be considered reasonably and forensically, and must be handled securely to ensure the integrity of the investigation. During an active enquiry, suspects should be advised by an expert and specialised defence solicitor to ensure that this evidence is submitted and applied fairly, as to ensure the presumption of innocence, even if charged.