Raleigh, N.C. — More than three decades after he was convicted of killing his pregnant wife and two daughters at their Fort Bragg home, Jeffrey MacDonald was in a Wilmington federal courtroom Monday trying to get a new trial.

The hearing, which is expected to last 10 days, hinges on DNA evidence that wasn't available during the 1979 trial and witness testimony that MacDonald's defense team says proves his innocence.

Prosecutors say MacDonald – now 68, remarried and still in prison – brutally stabbed his family to death with two paring knives and an icepick and beat them with a piece of wood in their apartment at 544 Castle Drive on Feb. 17, 1970.

During the trial, the state was never able to pinpoint a motive as to why a Princeton-educated doctor without a violent past would snap, kill his family, stage the crime scene and then inflict wounds on himself, making it appear that someone else had committed the murders.

Slideshow     MacDonald murder case photos

The crime garnered national attention after the release of a best-selling book, "Fatal Vision," and a made-for-TV drama.

Wade Smith, a Raleigh defense attorney who represented MacDonald at his 1979 trial, was the first defense witness to take the stand Monday. He testified about a 2005 phone call he received from retired U.S. Marshal Jimmy Britt, who wanted to "unload his soul" about an admission witness Helena Stoeckley told him as he transported her from South Carolina to Raleigh in 1979.

"Britt told me something had worried him. It was heavy on his heart and mind," Smith said. "He said he had been burdened heavily, morally."

Britt said Stoeckley, a known drug addict, admitted to being inside the MacDonald household during the murders and even described the children's hobby horse, Smith testified. Britt said he later witnessed Prosecutor Jim Blackburn threaten to indict Stoeckley with first-degree murder if she made those statements on the witness stand, Smith said.

“His story never happened. I never threatened Helena,” Blackburn told WRAL News in 2005. 

Blackburn, who left the U.S. Attorney's Office and went into private practice, later served jail time and lost his license for embezzling from clients.

Stoeckley, who has since died, later recanted her statements and said she had nothing to do with the murders. The Armed Forces Institute of Pathology examined Stoeckley’s hair roots and found that her profile was not consistent with any other crime scene samples tested, eliminating her as a source, according to court records.

Britt died in 2008, but his ex-wife, Mary Britt, took the stand Monday and talked about her memories from the MacDonald trial. She recalled her then-husband driving to South Carolina to pick up Stoeckley. When he returned, she said, "he was very excited" because Stoeckley had talked about her involvement in the crime.

"He said she described the inside of the apartment where the MacDonalds' lived," Mary Britt said. "She described it to a T."

Mary Britt also talked about her husband's struggles throughout the trial and how he had problems sleeping, something that was unusual for him.

"I woke up during the night. He was not in bed. I went looking for him, and he was outside sitting in a lawn chair," Mary Britt said. "He was very, very emotional. He described pictures of the MacDonald children (crime scene and autopsy photos shown in court). He said, 'Mary, I can't go back in there.'"

He was also upset after learning that Stoeckley's testimony couldn't be used at trial because "her brain is fried from the use of drugs," Mary Britt recalled her husband saying.

On the last day of the trial, Mary Britt testified, her husband came home early and said MacDonald had been found guilty. Jimmy Britt's boss asked him to lock up MacDonald, but he said no, he "was not doing any more of the dirty work" and told his boss he was going home, Mary Britt testified.

Mary Britt is expected to take the stand again Tuesday. Besides witness testimony, MacDonald's defense team plans to focus on three hairs found at the crime scene that don't match the family's DNA. 

MacDonald, who is not eligible for parole until 2020, has never wavered from his claim that he didn't kill his pregnant wife, Colette, and their two daughters, 5-year-old Kimberley and 2-year-old Kristen. He has maintained that he awoke on their sofa in their home at Fort Bragg as they were being attacked by four hippies – three men and a woman, who was chanting "Acid is groovy. Kill the pigs."

The word "PIG" was written in blood on the headboard in the master bedroom.

MacDonald’s attorneys want to use new technology called Touch DNA and Y-STR testing on the murder weapons, pieces of a surgical glove and fingernail scrapings. Touch DNA is so precise that it can come up with a DNA profile using just a few skin cells. Y-STR stands for "short tandem repeat" on the Y-chromosome and is often used in forensic DNA testing.

Despite new technology, the MacDonald case may still come down to the evidence that the jury weighed at the 1979 trial. Fibers from MacDonald’s pajama top were found all over the house, except where he says he struggled with intruders. Investigators say the blood patterns of his wife's blood on his pajama top were formed before he says the top was cut by a weapon-wielding intruder.

One problem, according to prosecutors, is that evidence in the MacDonald case went through the hands of numerous evidence custodians over the past 42 years, including the Army Criminal Investigative Command, the FBI, the clerk of court and the U.S. Marshal for the Eastern District of North Carolina.

The state also contends that Jeffrey MacDonald “has failed to demonstrate that the proposed testing is reasonable in scope, uses scientifically sound methods and is consistent with accepted forensic practices.”

U.S. District Court Judge James Fox will determine if MacDonald gets a new trial.