Robert Alan Durst was born on April 12, 1943, in New York City, to Bernice Herstein and Seymour Durst, a prominent real estate magnate. He was the eldest of four children in the affluent Durst family. Robert's grandfather, Joseph Durst, immigrated from Austria-Hungary and founded the Durst Organization, a major real estate company in New York City.

Durst's early life was marked by tragedy. At the age of seven, he claimed to have witnessed his mother's suicide, an event that reportedly had a profound impact on him. He attended Lehigh University, where he earned a bachelor's degree in economics, and later enrolled in a doctoral program at UCLA but did not complete it.

Despite being groomed to take over the family business, Durst's relationship with his family was strained. He was eventually passed over in favor of his younger brother, Douglas, leading to a permanent rift. In 2006, he accepted a $65 million settlement to relinquish any stake in the family enterprise.

Robert married Kathleen McCormack, a dental hygienist, in 1973. Their marriage was reportedly tumultuous, with Kathleen expressing fears for her safety. On January 31, 1982, she disappeared under mysterious circumstances. Durst claimed he last saw her boarding a train to Manhattan, but inconsistencies in his account and a lack of evidence led to widespread suspicion. Kathleen's body was never found, and she was declared legally dead in 2017.

Susan Berman, a close friend of Durst and the daughter of a Las Vegas mobster, was found murdered in her Los Angeles home on December 24, 2000. She had been shot execution-style. Investigators believed she was killed to prevent her from speaking to authorities about Kathleen's disappearance. A letter sent to the police, directing them to Berman's body, contained a misspelling ("Beverley Hills") that matched a previous letter from Durst, further implicating him.

In 2001, while living in Galveston, Texas, under an alias and disguised as a mute woman, Durst became entangled with his neighbor, Morris Black. After Black's dismembered body was found in Galveston Bay, Durst was arrested. He admitted to killing and dismembering Black but claimed self-defense. In a shocking verdict, he was acquitted of murder in 2003 but served time for bond jumping and evidence tampering.

Durst's life and alleged crimes were chronicled in the 2015 HBO documentary The Jinx: The Life and Deaths of Robert Durst. In the final episode, Durst, unaware of a live microphone, muttered to himself, "Killed them all, of course." This apparent confession, along with new evidence, led to his arrest in 2015 for Berman's murder.

In September 2021, Durst was convicted of first-degree murder for Berman's death and sentenced to life in prison without parole. Shortly after, he was charged with Kathleen's murder. However, on January 10, 2022, Durst died in custody due to natural causes before the trial could commence.