NORFOLK (CBS) -- It was a sensational trial. In 1999, a Wellesley doctor was charged with killing his wife and his secret life involving prostitutes was exposed.
Dirk Greineder has spent more than 20 years behind bars for a crime he says he didn't commit. He believes that because he cooperated with police, they focused only on him and didn't look for any other suspects.
It was Halloween morning in 1999. Dr. Greineder, an allergist with Brigham and Women's Hospital, and his wife Mabel, who he called May, took their dog out for a walk around Morses Pond in Wellesley. Greineder says he left Mabel to rest, and when he returned, he found her lifeless body bludgeoned and stabbed.
He says he called 911, telling the operator, "Help I'm at the park. Someone attacked her. It's definitely an attack."
Investigators say DNA evidence, along with a knife, a hammer and gloves were found in a storm drain near the scene of the murder. Greineder says all of the DNA evidence was trace DNA, a small amount that is easily transferred. He told the I-Team it was likely on his skin because the couple lived together and slept in the same bed.
But, Greineder believes what really convicted him was the evidence that he was secretly involved with prostitutes. He told WBZ-TV that close to 25-30% of the trial was based on the fact that he had called some escorts.
Greineder said he loved his wife and still does. He admitted that he and his wife had intimacy issues, which he said she would not deal with. He believes his indiscretion caused the jury to convict him.
Greineder believes his wife's murder was a thrill kill. He pointed to the Zantop homicides, when two Dartmouth professors were allegedly killed by two high school students for the thrill of committing the crime.
It is a theory Greineder's youngest daughter also thinks is true. She and her siblings have supported their father for more than two decades and still do.
Britt Greineder told the I-Team she does not believe her father killed her mother. "My father is an incredibly gentle human being. He is my hero and I am privileged to know him let alone be his daughter," she said.
Britt Greineder said her mother would want her to speak out. "My mother was a fighter. She would have told us to continue to stand up, continue to speak the truth because what other choice do we have?"
Greineder is now almost 80 years old. Now in the state's medium security prison in Norfolk, he spends most of his time working on prison reform. He and his children have spent years fighting for legislation that would give so called "lifers" a chance for parole after 25 years.
But Greineder admits any new legislation would likely not help him, telling the I-Team he understands the parole board looks for inmates to accept responsibility for their crimes. Greineder said that is something he cannot do.
"That's a big problem. I don't take responsibility because I didn't do it. I'm pretty much resigned," he said. "Unless I can still manage to reverse my case legally, I'm going to die in prison."
Greineder has one last chance to appeal. We reached out to the Norfolk District Attorney. Spokesperson David Traub told us "The jury in the Greineder trial heard forceful and compelling evidence of his guilt and we believe that the jury correctly found him guilty of murdering Mabel Greineder. Their verdict has been upheld at every level of appellate review."
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