New Evidence in 'Fatal Vision' Case

A former deputy U.S. marshal is coming forward with evidence in the case of a former Green Beret who was convicted of killing his wife and two daughters three decades ago.

Jeffrey MacDonald, 62, has steadfastly maintained his innocence in the 1970 slayings of Colette MacDonald, 26, and their daughters Kimberley, 5, and Kristen, 2, on a U.S. Army base in North Carolina. He says his family was murdered by a group of crazed hippies in an attack that left him severely injured. The crime was dramatized in the best-seller and TV miniseries "Fatal Vision."

"I did not murder my wife. I did not murder my children. I never hurt my wife or my children," MacDonald told "20/20" in 1990.

MacDonald is serving three consecutive life sentences in a federal prison for the murders.

Jimmy B. Britt, who was part of the security detail for MacDonald's 1979 trial, has stepped forward after more than 25 years to say he heard the lead prosecutor threaten to indict a defense witness for murder if she told her story in court.

Helena Stoeckley had testified she could not remember where she was that night, but she later said she was with the hippies during the murder. Police considered her a suspect early in the investigation because she fit MacDonald's description of one of the intruders he said attacked his family.

In newly filed court papers, Britt says he's "compelled to clear my conscience" by telling his story.

Former prosecutor Jim Blackburn strongly disputes Britt's allegation. He says Stoeckley never claimed to have been in the home.

The Associated Press reported that soon after the MacDonald trial, Blackburn entered private practice and later spent 3½ months in prison for forgery, fraud embezzlement, and obstruction of justice unrelated to the case. He has been disbarred and now works as a motivational speaker.

Stoeckley died in 1983. In a 1982 interview with a former FBI official hired by MacDonald, she described entering the MacDonald home with a group of Charles Manson-worshipping hippies.

"The phone rang. I picked it up and someone asked for Dr. MacDonald," Stoeckley said during the taped interview. "Well by that time I was pretty high on mescaline and I just giggled and said he wasn't there."

MacDonald's lawyers also may have news from DNA testing technology that did not exist in the 1970s.

"We expect that some of the hairs found at the crime scene will not match the MacDonald family member," attorney Andrew Good said. "And will therefore be evidence of intruders."

The AP also reported that Britt said that Stoeckley repeated her claims of being in the MacDonald home the night of the murders when he drove her from Greenville, S.C., to Raleigh, N.C., for the trial and that she even described a hobbyhorse in the family's home.

MacDonald's attorneys have asked a federal appellate court for permission to present the new evidence to the U.S. District Court in Raleigh.