LOS ANGELES — A former Manhattan neighbor of jailed real-estate scion Robert Durst testified Wednesday in Los Angeles court that his first wife, Kathie, was terrified of him.

Kathie McCormack Durst vanished in 1982, and Durst remains the prime suspect. Weeks before Kathie disappeared, she frequently ran from her Upper West Side penthouse terrace to her neighbor, Anne Doyle’s apartment, to flee Durst.

“Her hair would be disheveled, and it would be a little like a stray dog that would come out of the rain,” Doyle recalled on the stand in Los Angeles County Superior Court. A frail Durst, 76, donned a pair of black-rimmed glasses and a blazer two sizes too big as he stared intently at the witness.

“She’d be crying, she’d be shaking, she’d be a complete mess,” said Doyle, a former model who now lives in Australia.

Doyle told jurors that Kathie, then a fourth-year medical student, complained that Durst called her a “skank,” a “nobody” and an “idiot.”

“I know that she was terrified of him and that it wasn’t just emotional abuse,” the former neighbor said.

Doyle previously told prosecutors that Kathie, distraught and weeping, knocked on her window one night in her pajamas and said that Durst had beaten her, wanted to kill her and had a gun. She allegedly hid in Doyle’s bathroom for two hours.

The spark for that evening’s violent quarrel was Kathie’s alleged refusal to sign paperwork giving up all rights to Durst’s money and property, Doyle said. The couple’s marriage had soured and they were discussing divorce. Durst is from one of New York’s richest real estate families.

“She was a beautiful woman,” said Doyle as a photo of a smiling Kathie and Durst was displayed on an oversized monitor. Her testimony continues this afternoon.

Durst is on trial in Los Angeles County Superior Court for the slaying of his best friend, Susan Berman, in 2000 to allegedly keep her from cooperating with Westchester authorities on a new probe into Kathie’s disappearance.

But in an unusual twist, Deputy DA John Lewin has argued that he’ll prove Durst also murdered Kathie and another man, and the three killings are intrinsically connected.

In 2001, Durst went into hiding disguised as a mute woman in Galveston, Texas, where he killed his friend, Morris Black, dismembered his body and dumped him in a shallow bay.

LA prosecutors argued that Durst shot Black to keep him from revealing his true identity and whereabouts — even though a Texas jury acquitted him of murder in 2003 after he testified that he had acted in self-defense.