Cuba Gooding Jr thought he was having a "nervous breakdown" while filming
The 48-year-old actor plays the disgraced American footballer in the TV drama and recalls how he "couldn't stop crying" when he filmed one scene where he has to kiss the face of the late Nicole Brown Simpson, Simpson's wife who he was found not guilty of murdering, while she is in her coffin.
He said: "I had to rush out to my trailer, I just could not stop crying. I realised it was because, in real life, rooting for OJ, I had never acknowledged the victims.
"We had even gone to church to pray for Johnnie Cochran to get OJ 'out of his predicament'. I thought I was going crazy, having a nervous breakdown."
Gooding Jr admits he "did not care" if Simpson killed his wife or not when he was watching the trail unfold as a guy in his 20s, but has now realised the case was more about race issues.
When asked if he thought Simpson - who is currently in jail for armed robbery and kidnap - did it, he added to Radio Times magazine: "At the time, I did not care.
"Black people did not want to believe that Simpson did it.
"Doing this movie, I realised that it was not really about 'guilty' or 'not guilty', it was about making sure that the cops did not f**k with another black man."
* The People v OJ Simpson: American Crime Story screens on SoHo, Wednesdays, 8.30pm.
- Bang! Showbiz