The UK police holds more than four million DNA records, according to the annual report of the National DNA Database, published last month. This makes it the world's biggest DNA database by far.
More than 715,000 were added last year, and police want to grow it faster by lowering the threshold for which they collect DNA to include non-arrestable offences such as littering and speeding, according to responses to a review of the Police and Criminal Evidence Act (PACE).
The annual report showed that the database holds the DNA records of an estimated 200,300 individuals who have been acquitted, and another 139,463 who have been neither charged nor cautioned.
About 12% of all records are duplicates. This leaves the estimated total of individuals on record at 3.34 million, or about 5% of the UK population.
Police have taken samples from 382,746 crime scenes since 1995, and added nearly 69,000 last year. Since May 2001 it has found matches between database and crime scene samples in 182,612 cases involving 165,099 individuals. A single suspect was identified in 132,178 cases. Last year there were 49,247 matches with one or more crime scene samples.
The annual report shows a decline in the number or records removed from the database from an average 20,000 a year from 2002 to about 4,500 in 2006.