actually, I am pretty sure OJ did it, or at least was in it enough to be culpable. But I also believe that the not guilty verdict was due to not the incompetence of the LAPD or the prosecutors, they were very competent lawyers and cops.
TWO things tripped them up
1. arrogance/hubris/whatever
2. (related to the first) they manufactured evidence: planting the blood on the socks; the suddenly appearing bloody thumbprint; the missing blood from the blood sample; getting caught lying under oath right at the jury; etc etc etc -
they were used to having to try cases against outgunned (budget) and monstorously overloaded public defenders against whom most of these tricks would work becuase the PDs simply would not have the time and resources (investigators, etc.) to challenge them every step of the way.
Simply put, OJ did and the cops and their evidence lost credibilbty in the eyes of the jury becuse the jury simply decided they could not trust anything the State put on by way of police testimony or even scientific evidence.
Understand I am not defending OJ, I am simply pointing out facts and my impression of why the jury voted the way they did.