A Roman Catholic priest imprisoned for killing a nun 29 years ago told a newspaper that he is innocent, but a prosecutor and the victim's nephew wondered why he is only making the claim now.

The Rev. Gerald Robinson, now 71, was convicted in 2006 for killing Sister Margaret Ann Pahl in 1980 by strangling her and stabbing her 31 times in a Toledo hospital chapel. Church historians have said it's the only documented case of a Catholic priest killing a nun.

"I didn't do this," Robinson told The Columbus Dispatch for Sunday editions. "I have no idea why anyone would do it."

Robinson was sentenced to a mandatory term of 15 years to life in prison.

Lee Pahl, the nun's nephew, said he believed at the trial that Robinson was the killer and continues to believe it. He's also bothered that Robinson, who retired as a priest in 2004, has not been defrocked.

"As a convicted murderer, he shouldn't be allowed to keep his title as a priest," Pahl said.

The lead prosecutor said Robinson should have made his claim in court.

"For him now to come out and say he didn't do it — I would say to him, 'You missed your chance to say that when it counted,"' said Dean Mandros. "He didn't take the stand because he knew he couldn't answer the (critical) questions."

Lawyers for the Ohio Innocence Project are continuing tests to determine whether DNA under Pahl's fingernails matches someone else. The DNA doesn't match Robinson, and it also didn't match the Rev. Jerome Swiatecki, the late priest whom Robinson's attorneys believed should have been a suspect.

An 8-inch letter opener that was a gift to Robinson became the central piece of evidence that prosecutors used to tie him to the crime.

Robinson was charged with murder in 2004 after questioning by cold-case detectives.

"To my knowledge, they just wanted to have a case — a name. I don't have any reason why," Robinson said.

He said he was surprised by what came out at the trial.

"I couldn't believe it, the dramatics at what came out in the end by the prosecutors. I was surprised by a lot of the things those witnesses said at the trial," Robinson said.

Robinson said other prisoners in the Hocking Correctional Facility call him "Father" and tell him their sins.

"They know what I am," Robinson said. "They know why I am here. My case is no secret. It never was."