Real estate heir and convicted killer Robert Alan Durst has died at 78.

News 12's Tara Rosenblum was the first reporter to break the news on Monday. 

A grand jury in Westchester indicted Durst on second-degree murder charges on Nov. 1 in the disappearance of his first wife, Kathie Durst, who disappeared nearly four decades ago.

The millionaire real estate scion was also convicted of killing his best friend, Susan Berman, in Los Angeles in September.

Durst had additionally admitted to killing his neighbor in 2001 and was suspected of killing his wife Kathie in a fit of jealous rage.

He grew up a child of extreme wealth and privilege in Scarsdale, the oldest of four children to Seymore and Bernice Durst.

The multibillion-dollar Durst real estate empire controls numerous New York City properties, but his father was best known for creating the National Debt Clock in the 1980s.

Durst testified in his own murder case that witnessing his mother's suicide is what altered his life forever.

Strained relationships would become a theme, starting with his own brother.

Durst has said that his brother treated him miserably and that he would fight with him every chance he would get and embarrass him.

Durst was initially best known for his relationship with a young nursing student named Kathie McCormick - a woman he would later marry.

"Kathie liked him and that was the important thing," said Kathie's sister Virginia. "And then, of course, it turned into love."

In 1973, the couple got married in a private ceremony with just two guests - Robert's father and Kathie's mother.

It was a marriage that friends and family say quickly became victim to Durst's fiery temper.

"A lot of the stuff that Kathie was going through was kept to herself," said Kathie's brother, James.

By Christmas 1981, Kathie Durst told friends she was ready to leave - even having an affair with Bill Stephenson, the ex-husband of first lady Jill Biden.

Kathie Durst disappeared from their South Salem home just a few weeks later in early 1982, although Robert Durst didn't report it for five days, saying only that he dropped her off at the Katonah train station headed for Manhattan.

Her family immediately suspected he killed her, but no charges were ever filed.

"The moment the phone call came in, we both immediately said he did it, he killed her, we knew it," said Kathie's sister, Mary. "It should have been 10 detectives on but there wasn't, and there was no pressure."

Durst would use his power and influence to live a comfortable and quiet life until Christmas Eve 2000, when his best friend, Berman, was found shot to death inside her Los Angeles area home.

One year later, while Durst was living in Galveston, Texas, he killed and dismembered his neighbor, Morris Black. At a trial in 2003, he successfully argued it was in self-defense.

Durst's name faded from the news until 2015 when he agreed to participate in HBO's "The Jinx." In the special, he appeared to admit to each murder while microphoned but off camera.

"I killed them all," he said.

That special reignited interest in Durst and the death of Berman. The Los Angeles County district attorney filed murder charges against him for her death, and for the first time a jury convicted Durst of murder.

Durst was sentenced to life in prison.

Soon after, Westchester County District Attorney Mimi Rocah impaneled a grand jury to investigate Kathie Durst's disappearance.

It was a case that was working against time as the 78-year-old Durst was battling cancer and - within days of his sentencing for murder - a coronavirus infection.

His attorney Chip Lewis told News 12's Tara Rosenblum in a statement, "Mr. Durst passed away early this morning while in the custody of the California Department of Corrections. We understand that his death was due to natural causes associated with the litany of medical issues we had repeatedly reported to the court over the last couple of years. We will issue no further statements and will not entertain any questions out of respect."

Douglas Durst, Robert Durst's brother released the following statement, “Bob lived a sad, painful and tragic life. We hope his death brings some closure to those he hurt.”