Robert Durst’s arrest in New Orleans the night before Sunday’s finale of HBO docuseries “The Jinx” marked the end of a long journey for director Andrew Jarecki.

“We were obviously glad that they made the arrest. We were concerned that Bob was floating around, and we knew that Bob had been upset about Episode 5,” Jarecki told the New York Times Monday.

Durst, 71, seemingly confessed to three murders during the finale. “There it is. You’re caught,” he said. “What the hell did I do? Killed them all, of course.” He was not on camera when he made the startling admission, and Jarecki said Durst left his microphone on and was talking to himself in the bathroom.

The real estate heir was arrested Saturday on charges stemming from an investigation into the murder of his friend Susan Berman in Los Angeles in 2000. He had previously denied involvement in Berman’s death, as well as the 1982 disappearance of his wife, Kathleen.

Also Read: Robert Durst Charged With Murder of Susan Berman by LA County Prosecutors

During a phone conversation between Jarecki and co-writer/cinematographer Marc Smerling with the Times, the filmmakers explained that the bathroom confession came after a formal interview in April 2012 but the audio was not discovered until June 12, 2014. “That didn’t get loaded for quite a while. We hired some new assistants and they were going through some old material,” said Jarecki.

“We had reached out to law enforcement to try and get color about when they planned to arrest him. Because as civilians, one always assumes that law enforcement is going to move more quickly than they naturally do,” he said, explaining that they had also hired security. “For the first many months we were working on the film, we never felt that sense of being in jeopardy. But once that evidence was out there, and Bob knew that it was on national television, it raised a level of concern. So personally we were relieved that he was arrested when he was.”

Also Read: ‘The Jinx’ Timeline: Robert Durst’s Past, Present and Possible Future

As for what prompted Durst to finally come clean, “Marc and I both felt that confession in the washroom was really something that came bubbling out of him,” Jarecki said. “When you listen to it, it’s chilling because it feels like you’re channeling something from very deep inside a person, and that while he could argue that he was sorry that he did it, the truth is he seemed to be compelled to confess. And I think the confession on some level must be a relief to him.”

The filmmakers have not reached out to Durst since they discovered the audio but said that he was surprised when they asked about the letter to Berman in the second interview. He even called them to ask if they thought the letter was a big deal.

“I imagine after seeing that letter, it would be very difficult — I think it would almost be impossible to get him to sit down for a third time,” said Smerling.

For now, they don’t know if the audio will be used as evidence in the upcoming case. “Bob agreed that we could use any recording of him in any way we deemed appropriate,”Jarecki said. “He was well aware that he was miked all the time.”

Smerling went on to say: “Another hugely important piece of evidence was the original interview. It’s comprehensive. You’re seeing a small part of it. Bob admits to lying about his alibi after Kathie [his wife] disappeared. His whole demeanor is evidence, in my opinion.”

While they didn’t set out with the goal of getting justice, Jarecki said it “went from being more of a movie to being a bit more of a mission when we started to realize how open Bob was being.”

With an upcoming trial in Los Angeles, they are still in “filmmaking mode” and are “keeping their ear to the ground” in the hope of finding out what happened to Kathie.

Also Read: Robert Durst’s Murder Case Reopened as HBO Documentary Reveals New Evidence

Durst has denied killing Berman, but police have long believed he had a motive, allegedly wanting to silence her about Kathleen’s disappearance, another alleged crime he has long been suspected of but never been charged.

He was also charged in the 2001 shooting death and dismemberment of a neighbor in Galveston, Texas, but he claimed self-defense and was later acquitted.