RICHMOND, Va. — A federal appeals court spent about 45 minutes Tuesday questioning lawyers about the latest bid for a new trial for a former Army doctor convicted in the 1970 slayings of his pregnant wife and two daughters.

Jeffrey MacDonald, 66, is serving three life terms for the murders in a Fort Bragg home that spawned the book and television miniseries "Fatal Vision."

MacDonald wants the 4th U.S. Circuit Court of Appeals to allow him to introduce new evidence, including DNA tests and sworn statements by two people who are now dead, which he says supports his claim of innocence.

He has always maintained that four drug-crazed hippies killed his family.

In 1997, a federal judge ordered DNA testing in the case. Defense lawyers say a hair was found under the fingernail of one of his daughters and contend that DNA helps prove the theory of intruders.

"It's not Jeff's hair," Kathryn MacDonald, who married MacDonald in 2002, said after Tuesday's court hearing. "It's unsourced, and that is inexplicable evidence of actual innocence."

MacDonald's attorneys also argued Tuesday that Helena Stoeckley would have testified that she was in the home the night of the murders but changed her story after a prosecutor threatened to charge her with the killings.

Stoeckley has since died, as has Deputy U.S. Marshal Jim Britt, who said in court papers that he heard the prosecutor threaten her.

Prosecutors contend there is no reason to reopen these issues, saying the case has to end at some point.

"I don't know anyone who could do what he's done – to stand strong (and) never waiver for 30 years of wrongful incarceration," Kathryn MacDonald said.

She said she was encouraged by the questions asked by the three-judge panel. A ruling isn't expected for several months.