WILMINGTON, N.C. – "As sure as I'm sitting here, Jeffrey MacDonald is innocent!" Sara McMann cried out in court.
McMann described how she and her husband invited a troubled woman and her infant child to stay in their home back in 1982, a couple months after meeting them through a church friend's prayer request.
According to McMann, the mother, Helena Stoeckley, later confided that she had witnessed an infamous crime 12 years before, accompanying three men into MacDonald's Ft. Bragg, N.C. apartment during the pre-dawn hours of Feb. 17, 1970, when his pregnant wife and two daughters were murdered.
The testimony corroborates the former Army doctor's story that three men attacked his family and were accompanied by a woman carrying a candle who was chanting, "Acid is groovy, kill the pigs."
"Helena told me that the men that went did the murdering," McMann recalled. They told her "they were going to rough Jeffrey up and that she was going to become a wizard in (an) occult group."
Stoeckley died in 1983. But her story about being present at the crime was backed up Tuesday by her brother Eugene. In court, he described a conversation with their mother (also named Helena) prior to her death.
"My mother said Helena was there and MacDonald was not guilty of the crimes," Mr. Stoeckley testified.
Stoeckley also recalled an earlier argument he had with his sister.
"She told me to be careful because she had certain friends," he said. "She told me she also had an ice pick."
Jeffrey MacDonald's new wife Kathryn, who has never seen her husband outside of prison, was pleased with Mr. Stoeckley's testimony.
"He said exactly what happened," Mrs. MacDonald told reporters as she left the courthouse Tuesday. "He's unimpeachable."
Although the younger Helena Stoeckley was called to testify in Jeffrey MacDonald's 1979 murder trial, once she took the stand the admitted drug user denied having any recollection of the hours during the crime.
Defense lawyers are trying to prove the prosecution used the threat of murder charges to dissuade Stoeckley from testifying that she and others were present during the deaths of MacDonald's children and his wife Colette.
Wendy Router, who served as an assistant for the defense in the 1979 trial, said when she asked Stoeckley why she failed to mention the crime scene on the stand, Stoeckley explained, "They'll fry me, burn me, hang me…"
But Colette MacDonald's brother Bob Stevenson told reporters outside the courthouse that prosecutors had merely advised Stoeckley of her rights. Stevenson insisted the conflicting statements Stoeckley made when she was alive can not be trusted.
"Her mind is that of a drug-addled witness," Stevenson told reporters. "If you take a lie detector test, of what value is it to an insane person talking with a drug-addled mind. It's useless!"
The public narrative of Jeffrey MacDonald as a killer is spelled out in "Fatal Vision," the 1980s book and TV mini-series by Joe McGinniss -- the controversial author who, most recently, moved next door to Sarah Palin while writing a book about the former vice-presidential candidate.
In an essay published Monday on Breitbart.com, Palin writes, "I sympathize with MacDonald and his defense team because I saw firsthand the twisted way McGinniss operates."
Another author Errol Morris, whose documentary "The Thin Blue Line" helped free a Texas man convicted of murder, said he hopes his latest book "A Wilderness of Error" has a similar effect on the MacDonald case.
"The justice system has its flaws," Morris said. "But I believe that when all of the evidence in this case is presented, that it will be absolutely clear that there was a miscarriage of justice in 1979 and this man will be set free."
That's exactly what MacDonald's lawyers are asking for or, at the very least, a new trial. U.S. District Court Judge James Fox is expected to continue hearing evidence for the remainder of this week, and possibly through next week.
Jonathan Serrie joined Fox News Channel (FNC) in April 1999 and currently serves as a correspondent based in the Atlanta bureau.