Angeles police are testing a knife found a dozen years ago O.J. Simpson once lived — but it is far from clear whether it has any connection to his wife’s murder, a case has remained open since the former football star was acquitted in 1995, multiple law enforcement officials said.

The small, old buck knife was recently handed over by a retired LAPD traffic officer, who told police he was working on a film shoot 12 years ago when a construction worker gave it to him, explaining that he had found it on the perimeter of the property, the officials told NBC News.

It’s hard to know where the knife came from, let alone what kind of potential evidence, if any, exists on it, officials said. The Simpson house was demolished years ago.

Investigators also trying to confirm the ex-cop’s story to determine who’d handled the knife before he obtained it.

The retired officer told investigators that he went to police at the time and was told it was worthless, and could keep it, the officials said. But when he mentioned it to an LAPD detective recently, the detective told him to turn it over.

Knives remain an issue with the Simpson case because investigators never found the blade used to stab to death his wife, Nicole Brown Simpson, and her friend, Ronald Goldman, in June 1994. The owners of a high-end cutlery shop testified that Simpson had purchased a large knife from them weeks before the murder. The Simpson defense team produced a knife that they said was the one he’d bought earlier. That knife was tested and was found to have never been used for anything.

Officials told NBC News that the retired cop’s knife appeared cheap, with no obvious signs of evidence on it.

They described the testing as being done “just in case” it turned up something relevant.

Because he was acquitted, Simpson is immune from being prosecuted again. But no one else has been charged.

Simpson is in prison on an unrelated robbery conviction.