Jeffrey MacDonald, the former U.S. Army doctor and Green Beret convicted of murdering his pregnant wife and two young daughters more than four decades ago, will go before a federal judge again to present his claims of new evidence.

The Fourth Circuit Court of Appeals issued a ruling Tuesday, remanding the case to federal district court. The three-judge panel found that James C. Fox, a federal judge in Raleigh, improperly refused to consider DNA evidence and witness statements in a recent attempt by MacDonald to win exoneration.

For decades, MacDonald has maintained that his family was killed by four drug-crazed hippies who broke into his Fort Bragg home and knocked him unconscious. The killings in February 1970 and the murder conviction in 1979 are the backbone of "Fatal Vision," a book and television miniseries.

In his most recent bid for exoneration, MacDonald presented DNA test results from a hair found under the fingernail of his 5-year-old daughter, Kimberley. The DNA did not match anyone in the MacDonald family.

Other new evidence is a statement from Jim Britt, a retired federal marshal, about possible witness intimidation by James Blackburn, a prosecutor in the case. Britt claims to have heard Blackburn threaten Helena Stoeckley, a woman MacDonald claims was wearing a blond wig inside his house on the night of the murders.

Britt claimed Stoeckley admitted to being in the MacDonald house the night of the murders. After Blackburn threatened to charge her with the slayings, however, she testified she couldn't recall where she was that night. Britt and Stoeckley have since died.

The appeals court judges did not take a stand on whether MacDonald should get a new trial. Rather they acknowledged that MacDonald "has a daunting burden ahead" in seeking to establish he is eligible for relief based solely on his claims of innocence.

MacDonald, 68, is serving three life terms in federal prison.

anne.blythe@newsobserver.com or 919 836-4948