LOS ANGELES -- A so-called secret witness in the Los Angeles murder case against New York real estate heir Robert Durst was revealed Wednesday as a longtime friend of the millionaire and the woman he is accused of killing.

New York advertising executive Nathan “Nick” Chavin entered a courtroom through a back door with a personal security detail for his protection.

Chavin, 72, said he once considered Durst his best friend and thought the feeling was mutual with one exception: Durst was even closer with Susan Berman, the mutual friend Durst is accused of fatally shooting in 2000 at her Los Angeles home.

Get Breaking News Delivered to Your Inbox

Chavin was called to testify in a rare proceeding that is recording testimony from a few elderly witnesses and those who fear for their safety and may not be alive to testify at trial. In order to protect Chavin, his name was only provided to the defense two weeks ago - after he had traveled from his New York home to an undisclosed location in California - and not released publicly until he took the stand.

Prosecutors have suggested that with Durst’s estimated $100 million fortune, he could have witnesses knocked off. The defense said that suggestion is absurd and have pointed to Durst’s frail condition and the fact he’s in jail where his phone conversations are recorded.

Chavin did not offer any testimony connecting Durst to Berman’s killing before his testimony concluded for the day, but Deputy District Attorney John Lewin alluded earlier to incriminating testimony from the witness that could “bury” Durst.

Chavin described watching Durst’s first marriage deteriorate before his wife, Kathleen, mysteriously disappeared in 1982

Kathie Durst, as she was known, had confided in Chavin that she feared her husband.

“She said she was afraid of him,” Chavin said. “She never said he hurt her.”

He told of two violent incidents that Durst had described to him that didn’t involve his wife. In one, Durst said he had run over a woman police officer in the San Francisco Bay Area while creeping through traffic.

Chavin asked why he wasn’t in jail.

Durst replied: “What’s she going to do, go to her superiors and say, ‘He ran over me at 1 mph,’” Chavin said. “I think he did it in a prankish way.”

In another incident Durst kicked a man in the head who had been flirting with his wife. He said Durst never expressed regret and wasn’t upset the man sued him.

“The guy pissed him off,” Chavin said.

Chavin said he did not think Durst was responsible for his wife’s disappearance at the time, but that line of questioning was interrupted by the court’s recess for the day. He returns to the stand Thursday.

Defense lawyers tried unsuccessfully to bar a New York Times reporter from covering Chavin’s testimony.

Judge Mark Windham said the defense had only presented speculation that reporter Charles Bagli, who has covered Durst for years, would later be called as a witness in the murder case.

The defense said Bagli was friends with the “secret witness” might be able to contradict his testimony if later called as a witness. The defense didn’t want Chavin - unidentified at the time - to influence Bagli’s memory of previous interviews he conducted with the subject.

Bagli has written dozens of stories related to Durst’s suspected ties to his wife’s disappearance and Berman’s death, as well as his killing of a neighbor in Texas in 2001. Durst was acquitted of murder in that case after testifying that he shot the man in self-defense and then panicked and chopped up the body and dumped it in Galveston Bay.

A lawyer for the Times argued that the effort to boot Bagli from the courtroom raised “huge First Amendment issues,” and said the reporter was protected by a state law that shields journalists from testifying in court.

“It would be dangerous and, frankly, unprecedented for there to be a decision here that a reporter who interviewed a trial witness be excluded from covering that witness’s testimony,” attorney Theodore Kider said. He added that reporters who covered something long enough would eventually be prevented from doing their jobs.

A New York Times spokeswoman said the newspaper was pleased with the ruling.