(CNN) -- One of the most sensational and infamous murder cases in modern U.S. history returned to a courtroom Monday as former Green Beret doctor Jeffrey MacDonald sought a new trial in the killing of his family.
MacDonald was back in court in Wilmington, North Carolina, as his lawyers argued new evidence should be heard by a jury.
"We feel like evidence is coming in the way we want it to. So we are very pleased at this point," MacDonald lawyer Gordon Widenhouse told CNN affilliate News 14 Carolina.
MacDonald is serving a life sentence in the 1970 slayings of his wife and two young daughters in their Fort Bragg home. The 68-year-old has long maintained that they were beaten and stabbed to death by a group of hippies who broke into their homes, chanting "kill the pigs" and "acid's groovy."
MacDonald and his lawyers contend that DNA tests show that hair samples found underneath the fingernail of one of the victims did not come from a member of the MacDonald family and presumably were from one of the killers. The defense will also try to prove that the prosecutor in the criminal trial threatened Helena Stoeckley, a witness who had earlier confessed to being in the MacDonald home the night of the murders.
MacDonald told investigators that he was at home, sleeping on a couch, when he heard screaming. He awoke to find three men and one woman, whom he described as having blond hair and wearing a floppy hat. He was found with two stab wounds and a collapsed lung.
While an Army inquiry into the murders recommended that MacDonald not be court-martialed, a civilian federal jury found him guilty in 1979. He has been behind bars since 1982.
But in 2011, a federal appeals court ruled that MacDonald was entitled to an evidentiary hearing.
During MacDonald's trial, Stoeckley said she was not present and had no involvement in the killings. The defense insists the prosecutor, James Blackburn, pressured Stoeckley to alter her testimony.
Stoeckley, who had a long history of drug and alcohol abuse, died in 1983. Blackburn would not comment on the charge, citing Monday's hearing.
"I was the prosecutor in the case, and I did that job to the best of my ability," Blackburn told CNN. "I did it in great reliance of the evidence the government had, and we presented an honorable case and it was straightforward and it was based on good and competent evidence. And I agree with the jury's verdict."
The MacDonald saga has captivated the public's attention for decades. It also became the focus of the controversial and popular book "Fatal Vision" by Joe McGinniss. On television, millions watched a miniseries about the case and a memorable "60 Minutes" interview with MacDonald.
This month, Academy Award-winning documentary filmmaker Errol Morris spoke to CNN about "A Wilderness of Error: The Trials of Jeffrey MacDonald," his new book on the subject.
"We've been sold a bill of goods about this case," Morris said. "It's as phony as a three-dollar bill."
"There are many things about this case that rub me the wrong way, but principal among them was how the jury was asked to make decisions about his guilt or innocence with incomplete evidence; evidence that was withheld, corrupted and suppressed."