LONDON - Like so many great discoveries, it was an accident.
British scientist Alec Jeffreys realized 25 years ago Thursday that individuals have "DNA fingerprints," unique patterns of genetic material that can be used to identify them.
The discovery has solved thousands of crimes, put murderers behind bars, split and reunited families - and launched a fierce debate about privacy and human rights.
On the anniversary of his discovery, Jeffreys worried that police are using a database of DNA samples taken from suspects to brand innocent people "future criminals."
Britain's DNA database is the largest in the world, containing genetic profiles of more than 5 million people. Samples are taken from everyone arrested for a crime - and the information is usually retained even if the person is acquitted or freed.
Jeffreys, 59, said about 800,000 innocent people were on the database, raising fears of "discrimination, breach of genetic privacy, stigmatization - there's a whole host of issues here."
"Innocent people do not belong on that database," Jeffreys, a geneticist at the University of Leicester in central England, told the BBC. "Branding them as future criminals is not a proportionate response in the fight against crime."
British police can take DNA samples from anyone who is arrested, and keep the profiles even if the suspect is never charged - although the original blood, saliva or other genetic material is destroyed. The information is stored on one of the world's largest DNA databases, which was set up in 1995 and now holds information on 8 percent of the country's population. The FBI's national U.S. database, although larger, has information on about 0.5 percent of Americans.
Last year, the European Court of Human Rights ruled that Britain's "blanket and indiscriminate" policy of retaining genetic information breached the right to privacy.
In response, Britain agreed to remove hundreds of thousands of innocent people from the database, but said it would still keep the profiles of those cleared of serious crimes for up to 12 years. Critics, including Jeffreys, say the decision flouts the spirit of the court ruling.