It was the trial of the Century and, arguably, set the Kardashians on an even greater road to fame than they were already traversing but it seems  Caitlyn Jenner disagreed with the outcome and has since revealed she knew O.J. Simpson killed his ex-wife, Nicole Brown.

Caitlyn JennerCaitlyn Jenner has opened up about her thoughts on O.J. Simpson's trial in her new book

The step-father of Rob, Kourtney, Khloe and Kim Kardashian revealed in an interview that she and her ex-wife Kris Jenner both believed that American football player, Simpson was guilty of the murder of their close friend, Nicole and Ron Goldman.

Speaking about the 1990s trial, during which Kardashian father, Robert worked on the defence team of Simpson, Caitlyn said: "I know he did it. It was three people at the crime scene - pick a murderer. How hard is that?"

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She went on to say that Kris was also on her side in believing Simpson was responsible for the brutal murder of Nicole, a stance that made things incredibly difficult for her oldest daughters Kourtney and Kim.

She said: "The hard part during that trial was mostly Kourtney and Kimberly because they were a little bit older [than siblings Khloe and Rob Jr.] and their dad, who they love and adore - which they should - is on one side and we’re on the other."

In her memoir, Caitlyn wrote how Kim and Kourtney took their dad's side during the trial, placing themselves firmly in the small camp of people who believed that Simpson was innocent.

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The 67-year-old former athlete, who transitioned to Caitlyn in 2015, revealed even O.J.’s long-standing friend, Robert Kardashian, began to doubt his innocence.

In her book, Caitlyn claims that a few years after the trial, she and Robert were in a car together and he said: "I would’ve been okay with it if they had gotten him in the first trial."

O.J. was found not guilty of all criminal charges in his first trial back in 1995, but 'responsible' for the deaths of his ex-wife Nicole and waiter Ron Goldman in 1998 during his subsequent civil trial.

Caitlyn added: "The implication was obvious that he believed O.J. was guilty."

Caitlyn Jenner’s new book, The Secrets of My Life, is out now but is said to have caused waves in her family with its contents.