Kato Kaelin Gives His Take on 'American Crime Story' Cast

Kato Kaelin is being portrayed by Billy Magnussen in FX's American Crime Story: The People Vs O.J. Simpson, and he told ET how he really feels about the casting of the series.

"My hair was never that long," Kaelin pointed out to ET as he looked at a photo of Magnussen in character.

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"Otherwise, that's a great looking girl," Kaelin joked.

Kaelin was used as a minor witness for the prosecution in the 1994 murders of Nicole Brown Simpson and waiter Ronald Goldman, as he was staying in O.J.'s guest house at the time the crime took place.

"I thought he was guilty," Kaelin said. "The jury came up with a not guilty, and that's what the jury decided."

No matter the verdict, once he was called to the stand, Kaelin's life was changed for good.

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"I realized how powerful the media was because I walked in with people not knowing me and I walked out on the first day with people screaming my name," Kaelin said. "I realized this is the most powerful medium and that was before social media. It got so bad that I never wanted to go out."

Other cast members include American Horror Story's Sarah Paulson, who stars as prosecutor Marcia Clark; Malcolm-Jamal Warner, who plays O.J.'s friend and former teammate Al Cowlings; Friends star David Schwimmer, who plays Kim Kardashian's late father, attorney Robert Kardashian; John Travolta, who stars as attorney Robert Shapiro; Selma Blair, who plays Kris Jenner; and Oscar winner Cuba Gooding Jr., who portrays O.J.

"Robert Shapiro, I thought, was a very compassionate man and I think Travolta will be incredible," Kaelin said. "When they first had David Schwimmer casted I go, 'Are you kidding me?' and then I saw the picture. They did kind of the Pepe Le Pew and I said, 'Wow!'"

Despite his first-hand knowledge of the trial, Kaelin still anticipates that he'll be captivated by the series.

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"I can't wait for this to come out," Kaelin said. "I already know what the ending will be."

The 10-episode anthology series is based on Jeffrey Toobin's book, The Run of His Life: The People v. O.J. Simpson, and tells the story of the trial from the perspective of the lawyers.

Since the trial, Kaelin has accumulated a multimillion-dollar fortune thanks in part to the Slacker clothing line he developed with Rhonda Shear.