Dec. 18, 2012— -- A Michigan jury today found Jeffrey Pyne guilty of second-degree murder in the death of his mentally ill mother.
Pyne, 22, a former high school valedictorian, star athlete and University of Michigan biology student, had been accused of killing his 51-year-old mother, Ruth Pyne, in the family's Highland Township, Mich., garage on May 27, 2011.
Ruth Pyne had been bludgeoned and stabbed 16 times.
The trial began on Nov. 16. Pyne never took the stand, and his defense did not call any witnesses to testify.
When the verdict was announced in court today, Pyne appeared to be taken aback. Reacting to the verdict, he tilted his head slightly and blinked rapidly.
He had been charged with first-degree murder but the unanimous jury found him guilty of the lesser second-degree murder charge.
Pyne was well-liked in the Highland Park community, and many people did not believe he was responsible for his mother's death.
Prosecutors said he had been fueled by pent-up rage after years of abuse at the hands of his mother, who spent time in jail for assaulting him in 2010. Charges were dropped when she was treated at a hospital and promised to stay on her medication.
But Pyne's defense had said he was not involved in any way with his mother's death, claiming a stranger or strangers likely attacked Ruth Pyne.
The prosecution's case had been largely circumstantial. There was no physical evidence linking Pyne to the killing, but prosecutors did present photos taken shortly after the killing that showed Pyne's blistered hands.
Pyne has said the blisters came from throwing a wooden storage pallet at his job on a local farm.
Speaking to reporters outside the court today, Pyne's father, Bernie, said he was surprised by the verdict.
"I believe in my son's innocence and I wasn't able to get him home for his sister for Christmas, so it's not been a good year," he said, according to ABC News Detroit affiliate WXYZ-TV. "I have to go tell Jeffrey's 12 –year-old sister that it's just her and me now."
Jeffrey Pyne's ex-girlfriend, Holly Freeman, had testified during the trial that Pyne's mother was dangerous, delusional and off her medication. Freeman said Ruth Pyne would often assault her son, adding that Jeffrey Pyne was fearful of his little sister, Julia, being left alone in the house with their mother.
Ruth Pyne's sister said the guilty verdict provided "some justice."
"She was not the monster the media portrayed her to be," Linda Jarvie told reporters. "I am deeply saddened by my sister Ruth's senseless death. This was a heinous crime. Ruth Pyne was a victim."
James Champion, Pyne's attorney, also spoke after the verdict was read, saying: "I told him last Christmas that that was the last Christmas he'd spend in jail, and I had every intention of making that promise come true but we didn't get it done, so tomorrow we'll pick ourselves back up and figure out how to move along."
Pyne will be sentenced on January 29. He faces a possible sentence of 7 ½ years to 12 ½ years in prison.
ABC News' John Muller contributed to this report.