[holding answer 14 May 2009]: Information is not held centrally on the number of cases in which a DNA sample has contributed to a conviction. The National DNA Database (NDNAD), which contains profiles obtained from DNA subject samples, does not hold any information indicating either innocence or guilt. It is used as an intelligence database to assist the police in the investigation of crime and detection of potential offenders. The Police National Computer (PNC) holds information on convictions and whether a record exists on the National DNA Database. However, a manual case by case examination would be required to determine whether the DNA profile contributed to the conviction.
The European Court of Human Rights in the case of S and Marper recognised that biometric data "pursues the legitimate purpose of the detection, and therefore, prevention of crime". The National DNA Database contributes to public protection. Between April 1998 and September 2008, there were over 390,000 crimes with DNA matches, providing the police with a lead on the possible identity of the offender. In 2007-08, 17,614 crimes were detected in which a DNA match was available. They included 83 “homicides”, 184 rapes and a further 15,420 additional detections.