Los Angeles County Superior Court Judge Mark Windham handed down that punishment one month after jurors convicted Durst, 78, of first-degree murder for the Dec. 23, 2000, death of Susan Berman. Berman was shot at point-blank range in the back of the head inside her Benedict Canyon home.

Durst's lawyers said at Thursday's sentencing they plan to appeal.

Prior to her murder in 2000, Berman had been scheduled to speak to police about a fake alibi she allegedly gave Durst when his wife disappeared in New York in 1982, prosecutors said.

Kathie Durst has never been found, and no charges have ever been brought in connection with her disappearance.

After Berman was killed, Durst fell off the grid and landed in Galveston, Texas, where he assumed the name Dorothy Ciner and regularly wore a woman's wig, dresses and high heels.

Claiming self-defense, Durst was acquitted of the September 2001 killing of his neighbor Morris Black, despite admitting to dismembering his body.

Then in a 2015 HBO documentary series, "The Jinx: The Life and Deaths of Robert Durst," Durst appeared to confess to the slayings.

He went to the bathroom while still wearing a hot microphone, which recorded him whispering to himself: "You're caught! What the hell did I do? Killed them all, of course."

In statements before Durst's sentencing, Berman's family spoke passionately about the impact she, and her murder, had on them.

Denny Marcus called Berman, her cousin, an "absolutely extraordinary, unforgettable, brilliant person whose life was savagely taken from her at 55 when she had many years ahead."

"I know she's got her hand right here, she's on my shoulder, and she knows that I would do anything for her," Marcus said. She added that she could not hate Durst, because Berman made sure she always knew that "hate serves no purpose."

Berman's stepson, Sareb Kaufman, said: "I should have been working for a career I could be proud of, finding love, getting married and having children. Instead, I was forced to pay for memorials and bills that were not mine or planned for, having to spend what time I could manage to not be in tears or feel the hopelessness of going on another day."

Kaufman and David Berman, another of Berman's cousins, used their statements to call upon Durst to reveal the location of Kathie Durst's body.

"Let us know where Kathie's body is, so her family can get some closure," David Berman said.

"I hope in your final days and hours you will come to the same understanding and give the McCormicks what little they are asking for: to find Kathie," Kaufman said. "To lay her to rest appropriately, finally and at long last. This is the most important question ... the only thing you have to give any real value or ability to sway any opinion of you."

"In telling where Kathie is, perhaps you could find some small redemption in an act of humanity," Kaufman said.