NEW YORK (AP) — Donald Kagan had been in prison for murder for more than a decade when doubts about his guilt arose from an uncommon source: the former judge who had convicted him.

The reason was more extraordinary still: The now-retired, white jurist felt he had been swayed by bias against Kagan, also white, in the 1998 killing of a black man.

The judge pressed to get the conviction thrown out, but acting another jurist upheld it Wednesday, saying Barbaro's changed views of his own verdict didn't legally warrant throwing it out.

"This may be one of those cases that bothers me for the rest of my life," acting Brooklyn state Supreme Court Justice ShawnDya Simpson said.

Kagan sat still, his head tilted downward, after hearing her decision. His lawyers, Jeff Adler and Richard Mischel, plan to appeal.

Kagan, 40, shot an unarmed stranger, Wavell Wint, after they crossed paths outside a Brooklyn movie theater. Wint's friends testified that the two men bumped into each other, then struggled over a gun Kagan pulled. Kagan said that he defended himself after Wint grabbed the gold chain he was wearing, and that he had flashed the gun earlier to ward Wint off.

Then-state Supreme Court Justice Frank Barbaro heard the case without a jury, convicted Kagan in 1999 and sentenced him to 15 years to life in prison. An appeals court upheld the conviction, saying there was evidence that Kagan escalated a scuffle that stemmed from an argument, not a robbery attempt.

But Barbaro, as time passed, wasn't so sure. A former longshoreman and labor lawyer, onetime mayoral and congressional candidate and 24-year state assemblyman, the Democrat retired from the bench in 2003 after six years as a judge.

As he read news accounts about wrongful convictions, he started to question his verdict in Kagan's case. Re-reading the transcript, the longtime civil rights advocate became convinced his own hatred of anti-black racism had tainted his view of the conflict between Kagan and Wint, leading him to believe Kagan acted out of bigotry and to misinterpret facts that supported Kagan's self-defense argument.

"I saw a black man being killed by a white man, and that triggered my unconscious in ways I wasn't aware of," Barbaro said Wednesday by phone.

Although initially certain he conducted the trial justly, "I came to the conclusion that I had made a mistake," said Barbaro, who contacted Kagan's lawyers a couple of years ago. "I've been tortured by this ever since."

Barbaro said he was "outraged" by Simpson's decision and hoped Kagan's planned appeal succeeded.

"The man was not given a fair trial," he said.

Simpson encouraged the Brooklyn district attorney's office to re-evaluate the case, but prosecutors have argued the conviction should stand. "There is no credible evidence that the verdict was based on racial bias," spokeswoman Lupe Todd said Wednesday.

While Barbaro now feels his thinking was tainted by subconscious sympathies, they aren't apparent in the trial record, including a six-page decision explaining his verdict, Simpson said.

"This court finds Justice Barbaro's claims of bias and prejudice are mere afterthoughts or second guesses," she wrote.

Kagan has applauded Barbaro for coming forward with his misgivings. "Not many people would do that, especially after all this time," Kagan told the New York Post in a jail interview in December.

But Wint's relatives expressed anguish at revisiting the case.

"It was a little nerve-wracking, but I'm satisfied with the decision," Wint's sister-in-law, Lisa DeJesus, said Wednesday. "... Why overturn something now?"

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(Photo: 237/Chris Ryan/Ocean/Corbis)