In the end, Toshikazu Sugaya may owe his freedom to a single strand of hair. As he languished in prison on a life sentence for a murder he did not commit, his lawyer told him there was only one way out: disprove the false DNA evidence that had put him inside.

Sugaya, 62, spent more than 17 years behind bars for the killing of 4-year-old Mami Matsuda before being released a month ago. The girl's body was found dumped on a riverbank in Ashikaga, Tochigi Prefecture, in 1990. Police matched Sugaya's DNA from sperm retrieved from her discarded underwear.

Detectives had followed him for a year in search of evidence to support their belief that he was the murderer, said his lawyer, Hiroshi Sato. Police interest in Sugaya began after they discovered in preliminary checks that he shared the same blood type as the killer. They found an extremely shy man who they believed fit the profile of someone who would commit such an awful crime.