Home Affairs Select Committee report: The National DNA Database (pdf): "It is currently impossible to say with certainty how many crimes are detected, let alone how many result in convictions, due at least in part
Home Affairs Select Committee report: The National DNA Database (pdf):
“It is currently impossible to say with certainty how many crimes are detected, let alone how many result in convictions, due at least in part to the matching of crime scene DNA to a personal profile already on the database, but it appears that it may be as little as 0.3%—and we note that the reason for retaining personal profiles on a database is so that the person can be linked to crimes he/she commits later… it should be easier for those wrongly arrested or who have volunteered their DNA to get their records removed from the database.”