The case of Robert Durst has been fascinating to those who have followed his story on HBO’s riveting documentary series “The Jinx.” It has all the elements that captivate us: wealth, eccentricity, murder and mystery. But now that he has been arrested for murder and faces the death penalty, and his seemingly accidental murder “confession” aired on Sunday, the question of his mental health is going to fall on his defense team.

Is Durst mentally ill? A serial killer? Does he have a personality disorder? Over the years, he’s done strange things that have brought him back into the clutches of law enforcement -- for example, stealing sandwiches, urinating in public, and, well, killing and dismembering someone. And now this “confession.” Has he been trying to get caught?

“I believe he is mentally ill,” Dr. Rami Kaminski, a professor of psychiatry at Columbia University, told International Business Times. He noted that he was theorizing based on what he’d read and heard, as he’s never met or examined Durst. Kaminski  is sometimes called upon as an expert to assess the mental health of clients who've been accused of crimes, and he has also served as medical director of the New York State Office of Mental Health, overseeing the mental health of people, including serial killers and those who are in forensic facilities in the state.

“Since I believe he is mentally ill,” Kaminski said, “some of the unusual, seemingly irrational behaviors are indeed just that -- irrational. Applying our communal everyday logic to someone who is so clearly an outlier is hard. That is why I usually stay away from speculating on motives when it comes to someone obviously different from most. He could have been just a lousy liar by dint of his troubled mind.”

Dr. Kaminski talked to IBTimes about the strange case of Robert Durst, psychopathology vs. personality disorders, serial killers, and mental illness and the law.

International Business Times: Robert Durst is implicated in the deaths of three people. How many people does one have to kill to be considered a serial killer?

Dr. Rami Kaminski: In psychiatry, at least three with “cooling time” [i.e., time in between killings]; for the FBI, two people with cooling time -- in other words, not something like a shooting spree.

IBTimes: What is the profile of a serial killer?

Kaminski: In general in the U.S., they’re white males over the age of 30. Some are loners; some have regular families. Mostly, they’re not that bright -- average to low IQ. They mostly work in blue-collar, low-level work. A few are drifters; some have family members. It’s difficult to say what typifies a serial killer. What’s important for context here is there aren’t that many serial killers. From the 1800s until today, over 200 years, they’ve only chronicled maybe 400 to 430 serial killers.

IBTimes: What are some characteristics they share?

Kaminski: The No. 1 trait is psychopathology, psychopathy: They're people who have no remorse. They often have paraphilias (i.e., sexual deviations) -- for example, necrophilia, a fascination with having sex with dead people’s bodies. Some eat parts of the dead bodies. It’s sexual in nature. We are not talking about schizophrenic patients or people who are seriously mentally ill. Many people make this mistake. They don’t come across to people in society as crazy or psychotic, so to speak. They have very twisted sexual desires, rage against women and are often psychopaths: They don’t have remorse, guilt or anxiety over this.

IBTimes: What’s the terminology now: sociopath, psychopath?

Kaminski: It’s anti-social personality disorder.

IBTimes: Are there people with anti-social personality disorder who aren’t criminals who hurt people?

Kaminski: They don’t hurt people the way you would think about it, physically. Most if not all con artists, for example, have anti-social personality disorder. We have to remember most people do not end up being serial killers. It’s very rare. Most people with anti-social personality disorder are quite sophisticated about conning people. But they’re not necessarily violent.

IBTimes: And Durst, from what you’ve read?

Kaminski: He sounds like someone who is mentally ill.

IBTimes: He was determined not to be schizophrenic.

Kaminski: Schizophrenia is a very different condition. Most people who have it are the people you see talking to themselves on the street. Regarding Durst, it’s not nice to say, but they used to say that an eccentric is a nut with a million dollars in the bank. He slipped through the wire. He could be delusional and psychotic but not schizophrenic.

IBTimes: Can you say more about his mental health, given his bio?

Kaminski: This is why it’s so important to have someone evaluated. It’s hard to say based on tidbits of somebody’s life. He could be someone who is a serial killer with a lot of money, but they’re usually more sophisticated. And if he committed these murders, he mostly killed people he was close to. That’s unusual for serial killers. They usually kill anonymous people.

He sounds like someone who is angry and strange -- has had a strange, itinerant life, going back and forth to places, disappearing for a while, living in boarding houses. He could also be faking it to get attention, but if I had to bet on it, I would say he has a psychiatric illness. I don’t think he meets the criteria for serial killer because the killings weren't random.

IBTimes: Could he have anti-social personality disorder?

Kaminski: He seems like he has no remorse, and he has a need to draw attention to himself. He lacks, I think, the charming, suave way of the con artist. He seems like an odd person. Maybe if he didn’t have so much money and so many lawyers, he’d be languishing in prison somewhere. In my opinion, it’s the money that got him out.

IBTimes: What’s our fascination with serial killers and strange characters?

Kaminski: One of the ways that we are normal to each other is by being predictable. That’s how we get along. You go down the street, you pretty much predict how someone’s going to behave, and you’re going to behave in a way that would be predictable to them. It’s important for communal animals. The difference with people who have mental illness, you don’t know what they’re going to do next. There’s a sense of awe. That’s why we’re interested in the bizarre, unusual, unpredictable.

IBTimes: What is something you’ve learned as a psychiatrist you’d like to share?

Kaminski: There are certain areas of psychopathology that the courts don’t consider often. It’s a problem. The level of bizarre behavior and level of problems that people have is not often obvious from the way they behave, speak or the way they operate. So we tend to blame the poor schizophrenic patients who are totally innocent and not likely to do something bad. It’s something that’s very painful to psychiatrists. People are often scared of and vilify those who are obviously mentally ill -- people who are talking to themselves, who are delusional. They are usually so lost, frightened and lonely that it’s unusual for them to be involved in something like this. But we’re caught in that kind of thinking. It’s important to have more people with an interest in their cases.

Attorney Elizabeth Kase and I just got someone off who was about to go into prison for five years. It was so obvious he was not well. We were able to convince them he was mentally ill. The courts need to do more to be attuned to that.

IBTimes: Do you think Durst's defense is going to try to use a mental illness angle? Would it be successful, given the courts' record on mental illness as defense?

Kaminski: Yes, I do believe that if he is indeed found mentally ill and his guilt would be proven -- right now, I assume there exists only circumstantial evidence -- I would definitely go for not guilty by reason of insanity and send him for a long time to a hospital. I predict that is what would happen if those conditions are met.