There's an author out there who says the real killer was O.J.'s son Jason, a chef. In his book, he notes that Jason was never interviewed by the police, his alibi is sketchy, there was a lack of blood in certain parts of O.J.'s home that should have been found if O.J. was all covered with blood from the killings. O.J. was reportedly protecting his son, who has a history of violence and carried the kind of knife that was used in the killings. Plus, the murder weapon was never found.
I've seen better write ups than this one, but here's a link.
Well, that's the point. The police were so convinced it was O.J., they never even interviewed his son. They never found bloody clothes belonging to O.J., and the story works for me because it still places O.J. at the scene, but it addresses the lack of a murder weapon and the shortcomings of the blood evidence.