Is Millionaire Murder Suspect Robert Durst Insane?

See Robert Durst's bizarre childhood diagnosis.

Is millionaire-murder suspect Robert Durst insane?

His behavior in the HBO documentary The Jinx suggests he has been off his rocker for years, including one moment where he talked to himself.

He said, "I did not knowingly, purposely, intentionally lie. I did make mistakes."

We showed the video to New York psychiatrist Dr. Julia Samton.

She told INSIDE EDITION, "Here, we have a sociopath. Somebody who has a sense of entitlement, who's unable to empathize with the needs and emotions of others, who considers himself to be really above the law."

Durst was caught on surveillance camera checking out his estranged brother's Manhattan townhouse in 2013 despite a court order to stay away. He wandered up to a staircase to the front door and turned back.

Matt Birkbeck, who wrote A Deadly Secret about the case, says Durst's problems were well-known to his family.

Birkbeck told INSIDE EDITION, "I think he is absolutely psychotic. When he was ten years old, he was diagnosed with having severe psychological problems."

In an emotionless way, Durst described chopping up the body of a neighbor he says he killed in self-defense in 2001.

"I dismembered the corpse primarily with the axe, but some with the bow saw and I think another saw," he said.

Did Durst want to be caught?

Consider this: In 2001, when he was on-the-run after dismembering his neighbor, he was caught stealing a chicken salad sandwich from a supermarket despite having $38,000 in cash.

Perhaps Durst's craziest move was to sit down for an interview for The Jinx against the advice of his lawyer.

Dr. Samton added, "He really sees himself as bullet-proof."

That could be the biggest mistake of his life.