LOS ANGELES — It was yet another twist in the case that even two decades later remains at the center of American attention.

Warning the story behind it could well amount to nothing, police nevertheless said they are examining a knife that was reportedly found at the home where O.J. Simpson was living in 1994 when his ex-wife and her friend were stabbed to death.

The knife was believed to have been recovered by a construction worker tearing down the house. The worker then gave it to an off-duty police officer who was working as a security guard at a filming location, police said.

It was unclear when the knife was found and how long it was held by the officer, who is now retired. The knife was being analyzed by a Los Angeles Police Department crime lab for DNA or other material that could possibly link it to the killings.

Capt. Andy Neiman stressed Friday the authenticity of the story was not confirmed and investigators were looking into whether “this whole story is possibly bogus from the get-go.”

“It’s unusual how this all of a sudden becomes a huge story during this time,” Neiman added, referring to the popular “People v. O.J. Simpson: American Crime Story” anthology airing on FX.

Simpson was charged and acquitted in the slayings. Even if the knife is linked to him, legal experts say he could not be criminally charged again because of protections against double jeopardy.

“If they were going to find this knife and make it useful in the murder trial, they should have found it 20 years ago, and they didn’t,” said Loyola Law School professor Laurie Levenson. “It will just raise more questions about the incompetence of the investigation and probably lead to more books and more movies.”

The weapon used in the killings has been a mystery for decades. Other knives have surfaced during the case, but they were not linked to the crimes.

In 1994, a salesman testified at a preliminary hearing that he sold Simpson a knife before the killings.

The bodies of Nicole Brown Simpson and friend Ronald Goldman were found stabbed outside her home on June 12, 1994.

Simpson’s Brentwood mansion was torn down after he moved to Florida following his acquittal.