Transcript for Murder Case Reopens as HBO Airs Robert Durst Documentary 'The Jinx'
Back at 7:41 with a strange case of Robert durst. Heir to a real estate fortune he's been linked to three deaths dating back to the '80s but never been convicted even after admitting in court that he killed a neighbor, dismembered the body but now police have re-opened the investigation into one of those killings thanks to a new HBO documentary called "The jinx" in which durst goes on camera to tell his side of the story. Here's ABC's Ryan smith. Reporter: He's the eccentric real estate sky yon who made national headlines rasz a suspect in three deaths since 1982, cross-dressing and skipping bail along the way. He was arrested for the murder of a neighbor in galveston, Texas, in 2001. Claiming self-defense he was acquitted. The jury finds the defendant Robert durst not guilty. Reporter: His story now profiled in the current HBO documentary series "The jinx." Did not tell the whole truth. Nobody tells the whole truth. Reporter: But as Robert durst now jinxed himself? ABC news learning the 71-year-old now facing a re-opened investigation in los Angeles into the 2000 murder of his former friend Susan Berman. An investigation that could be bolstered by the show itself. Like this never before seen letter that Berman's stepson says durst sent to her a year before her death. It was clear enough I might be dancing with the devil. Reporter: He says it appears eerily similar to an anonymous note sent to police the day Berman died. A letter authorities say only Berman's killer could have written. The address written on the front is exactly like the cadaver note found with the misspelling the Beverly. Reporter: Durst denies killing Berman. I had nothing to do with Susan Berman and death. Reporter: Police long believe he had a motive allegedly wanting to silence her on a crime he's never been charged with, the disappearance of his first wife Kathleen now declared dead. Durst says he has no idea what happened to him. "The jinx" director Andrew Jarecki. What the audience will find when they get to the end is they're not scratching their head. Reporter: Hbo says they're proud of the series and equally fascinated to see what impact it may have. Durst has no comment. For "Good morning America," Ryan smith, ABC news, New York. Let's talk about that impact with Dan Abrams. He's here right now. You've been covering this case for years. Actually you appear in that HBO documentary in 2003 saying I can't believe he's been acquitted. Can you believe he cooperated in this documentary? I mean, it is astounding. Remember, this is a guy who the local authorities believe is connected to a 1982 murder of his wife, the 2000 murder of his friend to cover up the 1982 murder and then charged in 2001 in the case that he, of course, was acquitted in. So the fact that he even cooperated in this is astounding and so it's not that surprising to me that now that they have durst on camera and they have renewed attention to this case, that they've got themselves some new evidence and Robert durst could find himself in some big trouble. Got that letter where the handwriting may match. Absolutely and that becomes a crucial piece of evidence. I mean, they've been lacking that one thing to link him. They've always suspected it. They felt it in their guts. They said to themself, wait a second. How could it be anything else? If they can link that letter back to durst, they've got a crucial piece of evidence. Now, the problem here is that handwriting analysis tends to be as much art as it is science. And so you can certainly get someone on the other side to say, yes, well, these things do look similar and the misspelling is similar. There are other reasons to question. Just real quickly, he can be tried again -- he can be tried for the killing of the wife's disappearance or the friend but not tried again -- Any case where he hasn't already been tried they could charge him for. You can't retry him on the case where he was acquitted. Dan Abrams, thanks very much. Final episode of "The jinx: The life and deaths of Robert durst" is on Sunday, on HBO.
This transcript has been automatically generated and may not be 100% accurate.