Police said on Friday they were investigating a knife purportedly found at the former home of O.J. Simpson, the onetime football star who was acquitted of murdering his ex-wife and her friend in the so-called "Trial of the Century" that gripped the public two decades ago.

Forensic investigators were conducting tests on the knife, which was recently turned over to the Los Angeles Police Department by a retired motorcycle officer, Lieutenant Andrew Neiman told reporters at a news conference.

Neiman said the officer told investigators he was given the knife by a construction worker, who in turn claimed to have found it on the property in the Brentwood neighborhood of Los Angeles where Simpson's house stood at the time of the June 12, 1994 murders. The home has since been torn down.

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Police declined to elaborate on the timeline of when the knife, which was being tested for DNA evidence, was recovered but Neiman said it was possible that "the whole story is bogus from the get-go."

He declined to name the retired police officer or to say why the knife had been given to police only in the past two months.

"We still don't know if that is an accurate account of how this item came into our possession," Neiman said.

He appealed directly to the individual who found the knife: "... We would love to have you contact our Robbery Homicide Division."

Authorities have not described the knife in detail but the celebrity website TMZ reported it was a folding buck knife.

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The knife used to stab and slash Simpson's ex-wife, Nicole Brown Simpson, and her friend, Ronald Goldman, to death was never found at the time of his murder trial, which was carried live on most major broadcast television networks in the United States and transfixed much of the nation.

Simpson was acquitted of the murders in 1995 and cannot be prosecute again for the same crime under double jeopardy protections of the law.

Simpson was found liable for the deaths of Nicole Brown Simpson and Ronald Goldman by a civil court jury in 1997 and ordered to pay $33.5 million in damages to the victims' families, a judgment that has remained largely unfulfilled.

He was convicted in Las Vegas in 2008 of kidnapping and robbery in a bungled attempt to recovered memorabilia from his storied football career and was sentenced to a prison term of up to 33 years.

Highlighting the enduring fascination that the murder case holds for the American public, there were roughly 150 tweets per minute about O.J. Simpson on Friday, according to social media analytics firm Zoomph.

The new mystery surrounding the knife surfaced just as a popular new FX cable television drama series, "The People v. O.J. Simpson," chronicling the sensational trial, is airing. It debuted on Feb. 2