(CBS/AP) WILMINGTON, N.C.- More than 40 years after the murders of his pregnant wife and two daughters, former Green Beret Jeffrey MacDonald is getting another chance to try to prove his innocence in the case that was the basis for the book "Fatal Vision."
MacDonald is asking a judge to grant him a new trial. The hearing began Monday in a federal courtroom in Wilmington, with MacDonald's attorney saying if jurors in 1979 could have considered two new types of evidence in case, they would have found him not guilty.
Prosecutors chose not give an opening statement.
MacDonald is serving three life sentences for the 1970 murder of his pregnant wife, Colette, and their daughters, Kimberley and Kristen.
MacDonald's lawyer plans on concentrating on two bits of evidence - hairs that don't match MacDonald or his family's DNA and a statement from Jimmy Britt, a deputy U.S. marshal when the case was tried.
When those two things are considered with the rest of the evidence, "you would conclude no reasonable juror would find Jeffrey MacDonald guilty," defense attorney Gordon Widenhouse said.
And now, a book by acclaimed filmmaker and author Errol Morris says MacDonald was telling the truth all along.
Morris - whose 1988 movie "The Thin Blue Line" helped win freedom for a man wrongfully convicted of murdering a police officer - told Rita Braver of "" that DNA evidence not available at the time of MacDonald's trial now points to his innocence.
The first witness of the hearing was Wade Smith, who is testifying about Britt's statement. MacDonald's lawyer said that Britt heard prosecutor Jim Blackburn threaten Helena Stoeckley, a troubled local woman whom MacDonald had identified as one of the attackers.
A previous MacDonald attorney has said Stoeckley was prepared to testify she was in the MacDonald home the night of the murders until Blackburn threatened to charge her with the slayings. She later testified she couldn't remember where she was that night.
Lawyers expect the hearing could last up to two weeks.
MacDonald was in a tan prison jumpsuit for the hearing. He was shackled at the ankles, but not the wrist.