LOS ANGELES (AFP) - DNA testing on a knife found buried at O.J. Simpson's former estate has produced no matches, the celebrity news website TMZ reported on Tuesday.
"We're told the microbes in the soil degraded any DNA to the point it was impossible to get a meaningful result," the website said.
It added that police had also failed to find any hair or other sample that could provide a breakthrough in the case and that the "investigation is over."
Officer Tony Im, of the Los Angeles Police Department, told AFP he had no new information and that testing on the knife was ongoing.
"They are still doing testing and we are waiting for results," Im said. "We don't go by what TMZ says."
A construction worker found the buck knife with a five-inch blade buried on the perimeter of the property in 2002 or 2003, after Simpson had sold the estate, and gave it to a retired Los Angeles police officer who was working as a security guard at a nearby film shoot.
The officer has said that he initially alerted police about the discovery but was turned away. In January, he again alerted authorities who took custody of the knife.
News of the discovery led to speculation that it could provide a new lead in the 1994 slayings of O.J. Simpson's ex-wife Nicole Brown Simpson and her friend Ron Goldman.
The pair were found stabbed to death outside her home and the former football star was charged with the murders and endured one of the highest-profile trials in US legal history.
The murder weapon used in the slayings was never found.
Simpson was acquitted in the case but is now serving time in prison for an armed robbery and kidnapping in Las Vegas.