It’s been 20 years since the grisly murder of six-year-old JonBenét Ramsey captivated the nation, and although no one has ever been charged in her death, speculation once again fell on her brother Burke when he sat down for an interview with Dr. Phil last September.

Although the 30-year-old swore he didn’t kill his little sister, viewers were disturbed by his odd behavior, which included a lot of smiling — something that may stem from being socially uncomfortable, Dr. Phil noted.

MORE: JonBenét Ramsey’s Mother — What We Know About Patsy’s Involvement in Her Daughter’s Death

“He works remotely as a computer analyst,” the TV host said at the time. “He doesn’t go into the office. He’s not around people a lot. He’s very intelligent.”

Scroll down for more details about Burke’s involvement in the case.

One of the most popular theories is that Burke accidentally killed his sister.

Amateur sleuths seem to think that the then nine-year-old caused his sibling’s death when they were playing, but that it wasn’t on purpose. JonBenét was found with a broken skull and a garrote around her neck, with an autopsy confirming that she had been strangled. For many years, the public questioned whether John and Patsy Ramsey staged the rest of the crime to protect their oldest child.

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Burke defended his nonchalant behavior when talking about the murder.

“Yeah, well, I can tell you guys I was very emotional with the attorneys,” he told Dr. Phil. “I would just randomly cry out of nowhere. I guess it’s a combination of sitting in there with this weird guy that I never talked to before and asking me all these personal questions, it’s a combination of that and just kind of…at some point, you have to move on. I’m not saying I moved on then…I didn’t really get it. You have to stop crying at some point, I guess.”

He thinks a pedophile murdered his sister.

When asked whether he has any idea who committed the crime, Burke responded that it was “probably some pedophile in the pageant audience” who “saw her at one of the pageants.” He still “keeps the hope alive” that the case will be solved one day.