Actually, I believe that the matter of OJ's culpability in the deaths of his former wife and Ron Goldman was litigated in civil court and the judgment went against OJ. He was found to have caused their deaths.
Thus, it is not defamatory for Steve or you any of us to claim that OJ was responsible for their deaths. The word "killed" is probably within bounds. The word "murdered" is not since that has criminal implications and he was acquitted of first degree murder. I suspect that Steve and his former employer, Railstar, have little to worry about regarding any defamation claims regarding OJ.
One thing is certain. Wherever OJ is, the real killer is close by.