Robert Durst Says He 'Killed Them All' in Final Moments of HBO Doc

'The Jinx' ended with an unexpected twist on Sunday night.

The Jinx: The Life and Deaths of Robert Durst, HBO’s six-part documentary about the real estate heir suspected in two murders and the disappearance of his first wife, has been full of surprises in the first five chapters. Yet, none of them -- even the discovery of a letter that potentially links Durst to the death of longtime friend Susan Berman -- was more shocking than the final moments of Sunday night’s episode.

“What the hell did I do? Killed them all, of course,” Durst said to himself during a private moment in the hotel bathroom following his final interview with director Andrew Jarecki. Not realizing his microphone was still on, the man was talking to himself, upset with being backed into a corner by the filmmaker.

"What a disaster," Durst also said at one point. Was this a confession?

In 1982, Kathleen Durst, his first wife, was reported missing and hasn’t been seen since. Her husband has long been suspected by many to be behind her disappearance with many presuming he murdered her at the couple’s country home in Westchester County.

Nearly two decades later, Susan Berman -- a longtime friend of Durst and his spokesperson after Kathleen’s initial disappearance -- was killed, execution-style in her Beverly Hills home on December 23, 2000. Prior to her death, Berman told Durst she was to be interviewed by the police about his wife Kathleen. Her friend became a suspect, and it was in chapter five that the HBO documentary uncovered a letter from Durst with matching handwriting to the one believed to be sent to the police notifying them of Berman’s death.

That same year, Durst fled to Galveston, TX where he posed as a mute woman. In 2001, he was arrested for the murder and dismemberment of his neighbor Morris Black. Though he admitted to carving up the body, Durst convinced a jury that Black’s death was in self-defense. Durst was twice acquitted of the crime.

Over the weekend, Durst was arrested in New Orleans on a murder warrant in the California investigation into Berman’s death. His lawyer said he will plead not guilty when he's called into court. 

Durst’s brother Douglas, who refused to participate in HBO’s documentary, released a statement following the news of his arrest. “We are relieved and also grateful to everyone who assisted in the arrest of Robert Durst,” he said in a written statement. “We hope he will finally be held accountable for all he has done.”

On Sunday, HBO released a statement saying, "We simply cannot say enough about the brilliant job that Andrew Jarecki and Marc Smerling did in producing The Jinx. Years in the making, their thorough research and dogged reporting reignited interest in Robert Durst's story with the public and law enforcement."