Now, to a new development in one of the most sensational crimes in american history. The so-called fatal vision case. A former green beret, jeffrey MacDONALD, CONVICTED IN THE Murders of his pregnant... See More
Now, to a new development in one of the most sensational crimes in american history. The so-called fatal vision case. A former green beret, jeffrey MacDONALD, CONVICTED IN THE Murders of his pregnant wife and their two daughters. It's been the subject of a best-selling book, a tv mini series. Tomorrow, a new chapter. A convicted murderer will get a chance to prove his innocence because of dna. Tonight, abc's david kerley. Reporter: It was a gruesome crime that gripped the country. One of the nation's most controversial murder cases. Reporter: A pregnant mother, her two daughters, stabbed repeatedly and beaten to death at ft. Bragg. I did not murder my wife. I did not murder my children. Reporter: But green beret and MEDICAL DOCTOR jeffrey MacDonald was convicted of killing his family. Which led to a best-selling book, "fatal vision." Even a tv mini series. CAPTAIN jeffrey MacDonald, green beret doctor here on the base. Reporter: The killings came just months after the manson murders in california. MacDONALD HAS ALWAYS CLAIMED This case was similar. Hippies, three men and a woman, coming into his house, murder, his family. All these years later, oscar-winning documentarian erroll morris' new book about the case has raised new questions. No one has really established a strong case against him. I, myself, see no evidence which links him to the crime. Reporter: Tomorrow, macdonald gets another chance in court, asking that witness statements and hairs found in the house that don't match the family be admitted as evidence. Dna testing didn't exist when he was on trial. At the time, there were so many inconsistencies, it's the newly discovered dna evidence that casts another light. Reporter: But will it change his conviction of 33 years ago? I'm sitting in prison. I'm wrongfully convicted. Reporter: Those hearings in front of a federal judge could last a couple of weeks and it will be up to that judge to decide after all these years whether MacDonald gets a new trial. David? A lot of people watching this case. David kerley in washington, david, thank you.
This transcript has been automatically generated and may not be 100% accurate.