NEW YORK (PIX11) -- The Los Angeles District Attorney has reportedly reopened the investigation into the 2000 slaying of Susan Berman, a close friend of New York real estate scion Robert Durst, after an HBO documentary about Durst revealed new evidence in the cold case.

Berman was shot in the back of the head "execution-style" at her Benedict Canyon home in December 2000. Her case is revisited in documentarian Andrew Jarecki's "The Jinx: The Life and Deaths of Robert Durst," which aired part five on Sunday night. The series also investigates Durst's possible ties to Berman's death as well as to the disappearance of his first wife, who vanished in 1982.

Durst, 71, hails from the powerful Manhattan real estate family of the same name, who own or operate a number of skyscrapers in New York City. Berman was a good friend of Durst's for years and stood by him when his first wife, Kathie Durst, went missing in 1982 in South Salem in Westchester County. Kathie Durst is presumed dead. New York investigators sought to interview Berman in 2000 after the Westchester County DA's office reopened the Kathie Durst investigation.

In Sunday's watershed episode, Berman’s stepson found an envelope with a letter written by Durst to Berman in 1999. The block lettering on the envelope seemed to be identical to an anonymous note sent to the Beverly Hills Police Department on Dec. 23, 2000 alerting them to a “cadaver” at Berman’s house. This is the same day police believe Berman was killed.

Beverly Hills is misspelled as “Beverley” on both notes. The D.A.'s office has reportedly declined to comment.

Did @HBO's The Jinx Just Solve the Mystery of Who Killed Beverly Hills Writer Susan Berman? http://t.co/lvdX0vnh0D pic.twitter.com/e6KbSXHKqw — Los Angeles magazine (@LA_mag) March 9, 2015

The New York Times reports the "visibly shaken" stepson then shared it with "Jinx" producer Marc Smerling, who notes that it is "exactly like the cadaver note, down to the misspelling of Beverly."

After the Westchester DA reopened the probe into Kathie Durst's vanishing, Robert Durst fled to Galveston, Texas, where he concealed his identity by dressing like a woman. Durst was arrested in the 2001 shooting death of Morris Black, his neighbor in Texas who he admitted to killing, but in self-defense. Even though Durst admitted he dismembered Black, a jury found him not guilty in 2003.

Durst told the Times last week that he did not have the "faintest idea" who killed Berman or who was responsible for his wife's disappearance.

The sixth and final episode of “The Jinx” airs Sunday on HBO.