Section 63G of PACE allows a chief police officer to apply to the Biometrics Commissioner for the retention of DNA and fingerprints belonging to an individual who was arrested for, but not charged with, an offence provided that they are either:
a vulnerable person
associated with the person to whom it relates
necessary for the prevention or detection of crime
If the commissioner grants the request, the DNA and fingerprints may be retained for up to 3 years (with a possible 2 year extension if granted by a court). If not, they must be destroyed.