Transcript for Kato Kaelin Clarifies O.J. Simpson 'He Did It' Comment

We're back with a shocking, new twist to one of the most famous trials in u.S. History. It's been nearly 20 years since o.J. Simpson was found not guilty of killing nicole brown simpson and ron goldman. His house guest at the time of the murder, kato kaelin, o.J. Simpson's house guest, is now speaking out, saying he does think o.J. Committed that crime. Here's abc's cecilia vega. Reporter: It's been nearly two decades since the trial of the century. If it doesn't fit, you must acquit. Reporter: Now, one of the famous faces from that courtroom drama is back in the spotlight. And speaking out this morning, he says, for the very last time. What do you want to say to put this to rest? I'm done. Let everybody just go on with life. Reporter: Kato kaelin found his name splashed across headlines and rocketing across the internet thursday, after "the new york post" published this story. In it, kaelin points a finger directly at o.J. Saying, yes, he did it. But he was too scared back then to say that in court. Kato kaelin saying o.J. Did murder his wife. It has everyone talking. Why didn't he come out then? He was scared, right? He was scared. I'm scared of o.J. And i never met him. Reporter: But kaelin is fighting back. These are words never in my vernacular. Reporter: Instead, kaelin says he thinks o.J. Is guilty. But he knows no more than the rest of the country, which held its collective breath, waiting for the verdict. If someone said, you think he's guilty? I would say yeah. Reporter: If I can sk that question? It's t a question that can be asked. Reporter: It's a story line that he has stuck to. Kaelin was o.J. Simpson's house guest. He was staying at simpson's home the night nicole brown simpson and ron goldman were murdered. Known as much for his hair as his vague, rambling testimony on the stand. Have your memories, your recollections of those nights changed over the 18 years? I don't go and think about those memories. If there's a reason for me to come and it goes in my mind, i just happen to think about it. And I hope it passes right away. Reporter: These days, he hosts his own tv show in los angeles. He says he just wants to put this history in the past. I'm not the reason o.J. Simpson's innocent in the first trial. Reporter: You're not? I'm not at all. No. There's a defense. There's prosecutors. I was a witness. I said, I think he's guilty. And I said many, many times. I cannot prove it. In the first trial, the jury said he's innocent. Reporter: For "good morning america," cecilia vega, abc news, los angeles.

This transcript has been automatically generated and may not be 100% accurate.