Just to throw some petrol on the fire of debate about how long to keep DNA samples on the DNA database if someone hasn’t been charged with a crime, here is an article from the BBC that shows cold case reviews and random hits on the DNA database do occur: Rape conviction ‘backs DNA case’. The Defendant, and now convicted rapist, was arrested in 2001 following an assault for which he was never charged. His DNA profile was uploaded to the UK National DNA Database in 2007 (because of advances in technology) where it scored a hit against an unsolved, outstanding rape case from 1990.
Some will say this is an excellent example of why DNA samples should be retained – what price does society put on solving a rape? On the other hand, some will say that the small number of successful random hits like this are far outweighed by the number of people who consider their civil liberties and human rights are violated by having their DNA retained on a database when they haven’t been proved to have do anything criminal.