The estranged brother of Robert Durst, the real estate heir on trial for his best friend’s murder, told a court he feared his oldest sibling would kill him.

“He’d like to murder me,” Douglas Durst bluntly told jurors in Los Angeles County Superior Court.

Durst, 78, is charged with the murder of his best friend Susan Berman in 2000.

He is accused of shooting the writer because of what she might have known about the unsolved disappearance and presumed killing of his wife two decades earlier.

His brother Douglas Durst, chairman of one of New York’s largest commercial real estate firms, said he had not seen his brother in 20 years and they had not spoken since 1999.

He said Robert was angry and bitter over an acrimonious inheritance settlement for tens of millions of dollars.

Douglas Durst, chairman of the Durst Organization that owns some of Manhattan’s premier skyscrapers and 2,500 apartments, said he and his brother had fought since they were children.

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“He treated me miserably,” Douglas Durst said. “He would fight with me at every chance. He would embarrass me.”

Despite the bad blood, Douglas Durst said he was not happy to testify against his brother but co-operated with prosecutors under threat of subpoena.

“There are other places I’d much rather be,” he said.

Prosecutors say Ms Berman provided an alibi for Robert Durst after he killed his first wife, Kathie, in 1982 and that he silenced his friend to keep her from telling police what she knew about the disappearance.

Durst has pleaded not guilty.

Prosecutors have said Durst’s 2015 arrest was hastened by his apparent confession to multiple killings in the award-winning HBO television series The Jinx.

Durst was arrested on suspicion of Ms Berman’s murder one day before the airing of the final episode, in which he seemed to incriminate himself.

Douglas Durst told the court that his sister-in-law Kathie told him she planned to seek a divorce from Durst.

He said his brother told him that she had vanished a couple of days after he put her on a train to New York City from their lakeside house in Westchester County. Robert Durst said that was the last time he saw his wife.

“His tone was very neutral,” Douglas Durst said. “There was no great anxiety in his tone. It seemed a little strange.”

Kathie Durst has never been found, but she was declared legally dead.