There were three people known to be in the Boulder, CO home where 6-year-old JonBenet Ramsey was killed on Christmas night in 1996 -- her parents, John and Patsy, and her older brother, Burke, who was 9 years old at the time. For the first time, Burke publicly reveals details about what he says happened the night of his sister's unsolved murder.

In the video above, Dr. Phil asks Burke: "Are you aware of these different theories that are out there -- theories that you killed your sister, theories that your mother killed JonBenet, and theories that an intruder killed JonBenet?"

Burke, 29, responds: "Yeah, I know that we were suspects."

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When Dr. Phil pulls out the ransom note that the killer allegedly left -- which Boulder authorities believed could have been written by JonBenet's and Burke's mom, Patsy -- he asks Burke, "Did the handwriting look familiar to you at all? Had you seen it ever before?"

"No," Burke responds. "I've never really looked at it closely ... It's not something I really want to look at a lot, you know?"

"Does that look like her handwriting?" Dr. Phil asks, referring to Burke's mom, who died of ovarian cancer in 2006.

Burke says, "She would always bug me about having good handwriting and she would make me rewrite stuff to try to make me have good handwriting. It seems too sloppy."

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Watch more from this episode here. And, Dr. Phil’s exclusive interview with Burke continues Monday, September 19. Check here to see where you can watch.