Simpson was found not guilty in the slayings of his ex-wife, Nicole Brown Simpson, and her friend Ronald Goldman in 1995. While some believe Simpson committed the crimes, even new evidence in the case would not mean Simpson could be retried.
"The 5th Amendment ensures double jeopardy would preclude a second trial for O.J. Simpson," said Jody Armour, a USC law professor. "O.J. cannot be tried again" in the double murder.
In a civil trial in 1997, a Santa Monica jury found Simpson liable for the deaths. But the Goldman family has struggled to recover damages from Simpson.
Simpson was later convicted on robbery and kidnapping charges in October and sentenced to prison in Las Vegas. In 2008, a judge there ordered that items he stole from memorabilia dealers be returned to California and sold to satisfy part of that $33.5-million civil judgment.
The knife found in Brentwood was apparently turned over to a police officer a number of years ago by a construction worker who was helping to raze Simpson's mansion on Rockingham Avenue, police said.
At a press conference at LAPD headquarters Friday morning, Capt. Andy Neiman said the officer was a traffic cop and was working on a movie set when he was given the knife.
Detectives learned of the knife's existence last month, and are now investigating where it came from, according to Neiman, who cautioned that the investigation is still in its early stages.
Neiman told reporters it was unclear why the officer waited nearly two decades to hand over the knife.
Armour, the USC professor, said in the event the knife was somehow connected to the Simpson-Goldman murders, it could potentially involve others.
"Let's say a friend helped stash the evidence -- the knife -- and they get some proof from the knife of that role. Then there could be accomplice liability."
Armour said the knife may be more of "historical interest but not much legal consequences could come from it."
Attorney Carl Douglas, part of the legal team that secured Simpson's 1995 acquittal on Friday called the story of the knife "ridiculous."
Another of his former attorneys, F. Lee Bailey, told Fox 25 News that he thought the story was far-fetched.
"O.J. did not drop [the knife] on his property any more than he did the gloves. The whole thing is ridiculous," he told the station.
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