PRINCETON — Kerry Max Cook served over 20 years in a Texas prison — most of them on death row. But as DNA evidence would show in 1999, he was innocent. That year, Mr. Cook was released from prison with the help of Princeton-based Centurion Ministries, a secular non-profit that works for the release of innocent prisoners.

   ”He was a nice guy. I never felt he was guilty,” said Rev. Carroll Pickett, a former death-house chaplain at the Huntsville prison in Texas, who spoke at Princeton Theological Seminary last week.Addressing an audience of about 30 activists and seminarians, Rev. Pickett called Mr. Cook “a victim of Texas justice” but then added: “Throw that out—there’s no such thing as Texas justice.”

   Rev. Pickett, himself a Texan and a former Presbyterian pastor who ministered 95 men before their executions, has become an outspoken critic of the death penalty and a prominent voice in the battle over capital punishment. In 2008, he was featured in the award-winning documentary At the Death House Door, which was screened at Princeton University last Tuesday. The next night, at PTS, he encouraged Christians to play a more active role in fighting the death penalty.

   ”As a Christian, I cannot support the death penalty,” Rev. Pickett said.

   ”I used to be in favor of the death penalty because my grandfather was murdered and nothing was done about it. My father taught me, you gotta hang ‘em fast, hang ‘em high. That’s Texas,” he said, in a slow drawl. “But then I went to work at the prison.”

   His first day was April 1, 1980. Six inmates came to chapel, out of a prison population of 2200. Frustrated, Rev. Pickett tried to find ways to reach out to the men, who he said had, on average, a seventh grade education. The answer was music. Among other programs, he started several choirs, which drew the inmates to chapel. As he described it, being a prison chaplain was “full time ministry.”

   Rev. Pickett had intended to work at the prison for only a year. He stayed for 15.

   Life in prison ministry was hard, and not only because he was constantly on call. What were called “spiritual” tasks — from informing inmates of terminal medical diagnoses to dealing with prison suicides — fell to Rev. Pickett. Frustrated by his hectic hours, he said, his first wife left him. And he was “only stabbed twice,” a fact that he stated matter-of-factly and only in passing.

   As the death-house chaplain, he spent much time with inmates who were hours away from execution, helping them prepare their last words and, he said, getting to know them as people.

   ”Sometimes they have family, but often, you’re all they’ve got,” Rev. Pickett explained. “Nobody should die alone and without a friend. My God-given calling was to be their last friend.”

   One inmate, 27-year-old Carlos De Luca, had an especially strong impact on the chaplain. Mr. De Luca maintained his innocence up to his execution in 1989, the 33rd execution that Pickett saw. His case was featured in At the Death House Door, with evidence from a Chicago Tribune investigation suggesting that he was indeed innocent. Rev. Pickett had grown especially close to Mr. De Luca, who called him “Daddy” in his last hours, and maintains that Mr. De Luca was innocent.

   ”I wanted to quit at execution 33,” Pickett said. “He was just a little boy…I can still see those big brown eyes. And when he called me ‘Daddy,’ it got to me, because I had a son that same age.”

   After he retired in 1995, Rev. Pickett became an outspoken anti-death penalty activist, traveling around America to speak to legislators, and eventually, he said, convincing the Alaska state legislator to decide against the death penalty. He argued that Christians should encourage restorative justice, and reforming inmates, over the death penalty’s “eye for an eye” justice.

   ”80 percent of the inmates in our prisons are candidates for restoration. They just need guidance,” Rev. Pickett said. “Out of the 95 men I was with, who were executed, I’m confident that 60 of them, I would take home with me.”

   Rev. Pickett pointed out problems in the capital punishment system in Texas, where most of the United States’ executions take place. The state—and Texas Gov. Rick Perry — have faced harsh criticism from anti-death penalty groups, especially after a recent New Yorker magazine article raised concerns about the quality of evidence leading to the 2004 execution of Cameron Todd Willingham, who maintained his innocence.

   Among the issues Rev. Pickett discussed is the Law of Parties, under which a person facing felony charges can be charged with a second felony committed by an accomplice because he or she “should have anticipated” that it might occur.

   ”Out of 95 that I was with, 15 were convicted on crimes under a law called Law of Parties,” he said, adding that one was a mentally disabled young man. “They were just there. Someone else pulled the trigger—but they were there.”

   Rev. Pickett told his Princeton audience that his goal had always been to change “just one” mind about capital punishment, and that it was gratifying to know when he had done so.