The estranged brother of Robert Dust reluctantly testified in the real estate heir's California murder trial on Monday.

Douglas Durst told jurors "He'd like to murder me."

He added, "He treated me miserably. He would fight with me at every chance. He would embarrass me."

Douglas Durst, from Katonah, showed up at the California courthouse with his own private security detail because he said he was so afraid of Durst. 

Robert Durst, 78, is on trial for the 2000 murder of his longtime friend Susan Berman.

Prosecutors claim Durst killed Berman because he feared she would reveal what she knew about the disappearance of Durst's first wife, Kathie, who vanished nearly 40 years ago from South Salem.

Durst remains the prime suspect in that case

However, no charges have been filed.