PRINCETON, N.J. -- Two months ago, Daryl Burton was sitting in a jail cell in Jefferson City, Mo., serving the 24th year of his sentence for the shooting death of a gas station attendant.

On a recent Saturday, Burton stood in a leafy backyard under a white tent with about 125 other partygoers.

"This seems surreal. I'm still pinching myself," said Burton, 46.

"This is unbelievable."

Burton had been sentenced to 75 years in prison for the 1984 slaying, a crime he said he didn't commit. He was freed Aug. 29 after an eight-year legal effort by the Rev. Jim McCloskey and McCloskey's co-workers at the Princeton-based Centurion Ministries.

McCloskey has been laboring nearly 30 years to exonerate innocent prisoners, and hosted a gathering in his yard to celebrate seven men released from jail in the past two years.

"Each of these seven men spent anywhere from 24 to 30 years in prison for the crimes of other people. Collectively they spent 188 years in prison," McCloskey told the crowd, which included the seven men and their families, lawyers and investigators who worked on the cases, other exonerated inmates, and well-to-do Princeton supporters of Centurion.

In the Missouri case, Centurion investigators uncovered key witnesses who had never been presented to the defense.

Going to prison will change anyone, Burton said, "but when you are in prison for a crime you didn't commit, that just compounds the issue.

... You have to face physical, mental and emotional trauma, and you never know what's going to happen day to day. ... And you haven't done anything to be there."

The fight to clear a convicted inmate is long, expensive and full of uncertainties. "Once you are convicted, all odds are stacked against you," said Barry Scheck, a New York lawyer and founder of the Innocence Project, which exonerates inmates primarily through the use of DNA evidence. "To get a conviction vacated is extremely difficult."

Centurion has brought freedom to 43 inmates since its first case in 1983, poring over documents, re-interviewing witnesses or running down people the police never talked to.

"We're like the tortoise," said Kate Germond, who met McCloskey in

1986 after reading an article about him in The New York Times. She became Centurion's second paid staff member and is now its co-director.

Germond, 61, says it may take Centurion five years of investigating to decide whether to take a case. If the case is accepted, it typically takes another five years before the person has a shot at freedom.

Careful vetting, she says, is how they determine a person is truly innocent, because instincts are often wrong. "Sometimes, the nicest guys turn out to be guilty, and the jerkiest guys turn out to be innocent," she said.

Costs for each case range from $150,000 to $300,000, according to McCloskey. Overall, the organization has an annual budget of about $1 million, most of it from private donors.