O.J. Did It

If the glasses don't fit, you must acquite. Let's be honest here, O.J. killed Nicole. The real question is what did she do to make him snap? Maybe, she continued to nag him and he just lost it and stabbed her and then killed the witness. Or maybe he's just a sick individual who just had enough of her and decided to stab her, or maybe he accidently fell ontop of her with a knife a couple times and then when that friend of hers came out he tripped and fell on him a few times as well. Anything is possible.