O.J. Simpson O.J. Simpson

LAPD detectives were unable to obtain any conclusive DNA results from the knife that was buried on O.J. Simpson's property, TMZ reports.

DNA testing on the knife didn't yield any results because microbes in the soil in which it was buried would have degraded any traces that were there, according to TMZ.

The knife turned up a couple of weeks ago after a retired police officer, who had had it in his possession for more than a decade, turned it in. The former cop says a construction worker gave him the knife after finding it on Simpson's Rockingham property, which was razed in 1998. It's unclear why the police officer, who was off-duty at the time, took the knife home with him rather than handing it over to authorities.

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The LAPD became aware of the knife in late January, when the retired officer contacted a friend in the department and said that he planned to have the knife framed and put on his wall. The friend told his superiors, who ordered the retired officer to hand over the knife.

The department subsequently opened a top-secret investigation, believing that the knife may have been the murder weapon used to kill Simpson's ex-wife Nicole Brown Simpson and her friend Ronald Goldman in 1994. The investigation is now closed.