Director Andrew Jarecki speaks about the HBO television show "The Jinx: The Life and Deaths of Robert Durst" during the TCA presentations in Pasadena, California, in this January 8, 2015, file photo. [Photo/Agencies]

Durst, 71, who was arrested at a New Orleans hotel on the eve of Sunday's final episode, agreed Monday to face trial for the murder of Berman, who had vouched for him in public after his wife vanished.

The makers of "The Jinx: The Life and Deaths of Robert Durst" said Durst had waved off his lawyer's advice to stay quiet before granting them two lengthy interviews. They also say he knew he was being recorded throughout, and that they shared any evidence they gathered with police long before broadcasting the film on HBO.

The documentary showed filmmaker Andrew Jarecki confronting Durst with a copy of an anonymous letter that alerted Beverly Hills police to go look for a "cadaver" at Berman's address.

Durst offered that whoever sent it was "taking a big risk. You're sending a letter to police that only the killer could have written."

Then, in the final episode, Jarecki revealed another envelope, which Durst acknowledged mailing to Berman, that has similar writing in block letters and also misspelled the address as "Beverley."

"I wrote this one but I did not write the cadaver one," Durst said. But when shown an enlargement of both copies, Durst couldn't distinguish them.

Durst - still worth millions despite his estrangement from his family, whose New York real estate empire is worth about $4 billion - has maintained his innocence in three killings in as many states.

He was acquitted by a Texas jury in the 2001 dismemberment killing of his elderly neighbor, whose body parts were found floating in Galveston Bay. Lawyers said Durst - who fled Texas and was brought back to trial after being caught shoplifting in Pennsylvania - killed Morris Black in self-defense.