Durst's lawyer Chip Lews announced Durst's death in a statement and said he died of "natural causes."
Kathie Durst went missing nearly 40 years ago when she was 29 years old. While her body was never discovered, her family had her declared legally dead in 2017.
On Thursday the 78-year-old real estate heir was sentenced for the murder of friend Susan Berman.
Nearly one month after Robert Durst was found guilty of Susan Berman's murder, the New York millionaire has been sentenced to life in prison.
The plan to indict the real estate millionaire comes shortly after a grand jury found him guilty of killing his friend, Susan Berman, who knew about his ex-wife's death.
After months of testimony and hours of deliberation, a jury determined the 78-year-old real estate heir guilty in the 2000 shooting of Susan Berman.
Durst drew massive public attention as the subject of a 2015 HBO true-crime docu-series, "The Jinx," in which he allegedly confessed to killing his wife.
Robert Durst, 76, is on trial in Los Angeles for the murder of his friend Susan Berman.
Durst, who made a fortune in real estate, has been held in a Louisiana jail since being arrested in March.
A federal case in Louisana is still pending for similar charges, as are charges of murder in California.
Durst was acquitted of the murder of his neighbor Morris Black.
Charatan is a leading investor in a company that owns dozens of properties in New York City.
Durst's attorneys have sought to expedite his extradition to Los Angeles County on a murder charge.
"That song is just about a horny werewolf," not about "killing anybody," Mark Oliver Everett says.
Robert Durst also once beheaded a human, but was acquitted of murder charges.
Durst may have been booted from his namesake company, but his real estate connections live on.
It could help the defense build an insanity plea.
Robert Durst, subject of HBO documentary "The Jinx," is arrested in New Orleans on a first-degree murder charge one day before the last episode is set to air.