A jury of seven men and five women found a Boston doctor with a secret life guilty Friday of first-degree murder in the bludgeoning and stabbing death of his wife of 32 years.

Dirk Greineder, 60, the allergist with a penchant for Internet porn and prostitutes, winced as the verdict was read.

Only feet behind him his three children, who stood by their father throughout the trial, sat hand-in-hand, bowing their heads and shutting their eyes as the verdict settled in. Opposite the children, Ilse Stark, the victim's sister, rose with tears in her eyes and stared at Greineder as he was escorted away in handcuffs.

The jury, which took nearly 30 hours over four days to arrive at their decision, rejected Greineder's claims that a stranger attacked and killed his wife on Oct. 31, 1999, in a park the couple frequented near their Wellesley, Mass., home. Mabel "May" Greineder, 58, was slain during a morning walk with her husband at Morse's Pond. The doctor was later charged after physical evidence linked him to the crime.

After a short recess Friday, Greineder stared blankly as he was sentenced to life in prison without the possibility of parole, a mandatory sentence under Massachusetts state law. Defense attorney Martin Murphy said he will file an appeal.

"I think we have already been sentenced," Ilse Stark told the packed courtroom before the sentence was imposed. "We've been sentenced to a life without my sister. My grandmother used to say when a person dies, a library burns. With the loss of my sister, the Smithsonian is gone."

The Crime

The path where Mabel Greineder was killed

Prosecutors argued that Greineder killed his wife because the couple's marriage was deteriorating and because she had discovered his online pornography habits, real-life trysts with chat room couples and encounters with prostitutes.

The doctor continued to maintain his innocence, claiming he separated from his wife that day after she hurt her back and continued ahead with the family dog. He testified that he returned a short time later to find her lying in the path, dead.

During the five-week trial, some of which was held in the historic, but sweltering, Sacco and Vanzetti courtroom in Dedham, Mass., lawyers presented almost 500 exhibits and 70 witnesses.

Though the case included testimony from a prostitute, two sex Web site operators and a chat room couple Greineder solicited for sex, prosecutor Richard Grundy relied largely on physical evidence to paint Greineder as a scheming murderer.

In his closing statement, Grundy urged jurors to use their common sense. "The evidence that speaks the loudest," he said, "is that which is the simplest."

Speaking to Court TV after the verdict, jurors said they tried to consider the evidence in a methodical manner during four days of deliberations. "There was an awful lot of information just to be put together again," jury foreman Stanford Smith said.

Cheryl Nixon, a juror on the case, said she and the others tried not to be swayed by the emotional testimony from Greineder, his three children, Ilse Stark, and Belinda Markel. "We as jurors have emotions," she said. "We learned to rely on each other to help us through some of the emotional issues."

"We were given instructions not to follow our heart and emotions even though that’s what every human being wants to do," she said.

The Evidence

Greineder was linked to one of the murder weapons, a palm-sized pocketknife, through DNA found on the knife that only one in 2,200 other white males would match.

His DNA was also found on one of two gloves used in the killing and discarded in the park that morning. Only one in 680,000 white males would match that sample.

"I think DNA was a brick in this wall," prosecutor Grundy said after the verdict, referring to the importance of all the evidence combined.

After the murder, Greineder's windbreaker was heavily marked with blood from his wife — he testified that he tried to pick her up — but a police photo showed his hands were remarkably clean, suggesting they had been covered.

Greineder's blood-spattered sneakers

Other important evidence included testimony from a blood spatter expert who said marks on Greineder's windbreaker and Reebok running shoes were caused by impact spatter from a blunt object hitting exposed blood.

Defense lawyer Martin Murphy tried to focus the jury on the strength of the Greineder family, not on the salacious testimony from his client's secret life or the glaring physical evidence.

"The evidence shows a man guilty of adultery, guilty of infidelity, guilty of using the Internet in … in ways that are disturbing," he said during his closing argument. "But it doesn't say anything about murder."

Murphy introduced a complicated "transfer" theory to explain why Greineder's DNA was found on the knife and glove. A forensic scientist testified that it was possible for Greineder's DNA to have traveled from a towel he used to wipe his face to his wife's face, and then to the killer and the murder weapon during the attack.

Mabel Greineder

Greineder's defense was supported by testimony from his children, Colin, 26, Britt, 28, and Kirsten, 30, who believed firmly in their father's innocence and in the strength of their parents' marriage.

Greineder, who has lost about 30 pounds since his arrest, also took the stand in his own defense. "I couldn't imagine living without her, she was truly the best person I had ever known," a tearful Greineder said. "Life with May was so much more than a sex life. It was all about sharing, about caring, it was about doing little things like the crossword puzzle... Most importantly, it was all about family, raising the kids."