DNA Samples Stir Doubts but Police Detectives Find Them Invaluable

The document means little to the disability support pensioner, who is illiterate. But he does notice that his name is spelled incorrectly and his date of birth is wrong.

“He explained that he couldn’t read the letter,” says the man’s lawyer, Redfern Legal Service police powers solicitor David Porter. “But we can surmise on the basis of what the police used in their letter that he had never served a sentence for a violent ­offence.

“It had been a number of years since he had come into contact with police. His last period of imprisonment was 15 years ago.”

This year in NSW alone, hundreds of people have had similar knocks on the door from police officers seeking a sample of their DNA via a mouth swab. It...