Warney was convicted in 1997 of the slaying. The case against him was largely based on a confession he gave in 1996. His lawyers contended that the admission was riddled with errors, and were the rambling of a man with an IQ of 68 who suffered from AIDS-related dementia.

The confession did contain some facts consistent with the crime scene, and defense lawyers now argue that police must have given those facts to Warney then included them in the confession. Warney did know Beason and may have been familiar with Beason's city home, according to trial testimony.

District Attorney Michael Green also said today that an inmate has confessed to the slaying, and that his admission was consistent with the crime scene evidence. Green would not identify the inmate, but said the prisoner said he acted alone and did not know Warney.

That inmate confessed on Thursday, Green said.

The Innocence Project, which uses genetic testing to try to free the wrongly convicted, has challenged the local DA's Office for two years to test evidence in the Beason slaying, but prosecutors had legally fought the requests.

Green said today, however, that he asked the Monroe County Public Safety Laboratory in February 2005 to test evidence from Beason's home because there was a theory that Warney might have had an accomplice.

"We theoretically could have had a killer walking the street," Green said.

Because of a backlog at the lab, months passed before testing could be conducted. In February of this year, tests showed the presence of one individual's DNA on clothing and blood found at the home, Green said. That DNA matched the inmate, whom defense lawyers say is Johnson.

Warney originally was charged with first-degree murder, which was then a death penalty-eligible offense, but a grand jury instead indicted him on second-degree murder. While it was a potential death penalty case, the charges against him drew national attention.

"Warney's confession appears to be the rantings of a man who has only a passing acquaintance with reality," wrote Bob Herbert, a columnist with The New York Times, who contended that Warney should not face the death penalty because the evidence was so shaky.

One of Warney's original attorneys, William Easton of Rochester, was so sure of Warney's innocence that he consented to let prosecutors take a blood sample from Warney without a court order. None of the blood that forensics technicians were able to test from the crime scene matched Warney's.

Other blood was found at the scene that did not match Beason's or Warney's.

Warney was prosecuted by Richard Keenan, then first assistant district attorney and now a County Court judge. Keenan, relying on testimony from forensics experts, argued at trial that the blood at the scene could have been there for months and could simply have come from someone who cut himself shaving while visiting Beason.

Easton said that Warney's case should show people that convictions aren't always sacrosanct, and there can be legitimate reasons to revisit questions about the guilt of people.

"I think this case is a cautionary tale to anyone who believes that the criminal justice system operates in a fair and flawless way," Easton said Monday.

There were reasons to suspect Warney of the crime, based on some of his past history. He had felony convictions, including robberies in which prosecutors said he beat elderly victims.

Warney supporters argued that he had been released from prison in 1993 and had not engaged in any more crimes since then. And his behavior was akin to that of a person who could wrongly confess to a crime, his attorneys said.

Only weeks before the Beason slaying, they said in court papers in 1996, Warney was admitted to a psychiatric unit at Strong Memorial Hospital "after allegedly pulling fire alarms and reporting false incidents."

Warney exhibited symptoms "consistent with impaired cognition and/or psychotic behavior," psychiatrists determined.

Approached by Warney's brother, David, the Innocence Project and Thompson agreed two years ago to take on Warney's appeal. They argued that more sophisticated testing was now available which could help resolve unanswered questions.

The DA's Office opposed new testing, writing in court papers that "DNA results now would add nothing significant to what we already know or what the jury knew at the time of trial."

The jury was told that Warney may have had an accomplice, even though he said he acted alone.

In 2004, state Supreme Court Justice Francis Affronti rebuffed a bid for DNA testing. He decided that Warney's defense had not met the legal threshold to require testing, and that claims that tests could show someone else had committed the killing were "too speculative."

Thompson said the DNA tests now show the fault of that ruling.

"This proves that the testing that was requested and the possibility of a favorable result (for Warney) was not too speculative," he said.

Easton said that had the grand jury indicted Warney for first-degree murder, he could have faced execution.

"Doug Warney could have faced the death penalty for a charge he is ultimately innocent of, and he has lost the last 10 years of his life in prison for a crime he demonstrably did not commit," Easton said.