O.J. KICKS OFF HIS OWN INVESTIGATION

O.J. Simpson offered a $500,000 reward for information leading to the arrest and conviction of the alleged real killer and set up a toll-free number for people to call. O.J.'s defense team also announced that it was hiring its own investigators to prove Simpson's innocence. A calculated public relations move? Definitely, says Vivian Berger, a professor at Columbia Law School and an expert on criminal law. But, she adds, "it's conceivable that with the trillions of calls they will get, they might get something that's useful to them." ATTN WOULD-BE TIPSTERS: that number, 1-800-322-3632, won't be plugged in until Friday.In other news, preliminary DNA tests from the now infamous, blood-splattered white Bronco showed no sign of blood from either Nicole Simpson or Ronald Goldman, the Associated Press says, citing a source close to the investigation.