Test have shown that a knife reportedly found near the former home of OJ Simpson is not a murder weapon.
Despite a large amount of evidence, the retired American football star was acquitted in the stabbing deaths of his ex-wife and her friend in 1995.
Police never found the murder weapon in that high-profile case, which captivated the US for more than a year.
He was later found legally responsible for the deaths of Nicole Simpson and Ron Goldman in a civil case.
Simpson, who is currently serving a 33-year sentence for armed robbery and kidnapping in Las Vegas, cannot be prosecuted again under US law for the murders.
Los Angeles Police had been sceptical that the weapon was tied to the Simpson and Goldman murders.
Police said at the time that the knife was a utility-type knife and was not consistent with the one used in the crime, but still ordered forensic tests.
The case recently returned to prominence with the airing of the TV mini-series American Crime Story: The People v OJ Simpson.
According to police, someone claiming to be a construction worker found the knife at Simpson’s former home when it was razed in 1998.
He gave the knife to a police officer who was working on a film set near the property.
The police officer kept it, thinking the case was closed. But the officer, now retired, recently told a colleague about the weapon, as a result of which the current investigation was launched.