Los Angeles police recently discovered that a piece of potential evidence was never turned in as evidence in the O.J. Simpson murder trial because it was kept by an officer as a souvenir. A possibly blood-stained knife that was found on the Simpson property by a construction worker is now being tested after the incident has come to light.

The potential weapon was unearthed while construction was taking place at Simpson's Brentwood, Calif., estate and passed on to the officer, who was working as a traffic cop at the time. The cop, who is now retired, planned to keep the knife as a memento of the high-profile case, in which the murder weapon was famously never found.

The theft was only discovered this year when the unknown officer retired in January. He was reportedly working as security for a movie team close to the Simpson estate when the construction worker discovered the possible weapon and turned it over to the officer, who then neglected to take it further.

The LAPD only heard about the object - which is reportedly a folding buck knife - after the retired officer contacted a friend at the Robbery Homicide Division (RHD). The officer allegedly wanted the Departmental Record number for the murder case so that he could engrave it on the knife before having it framed.

It is unknown when the weapon was discovered, with sources estimating that it was between 1998 - just three years after the murders - and "several years ago." There have been claims that the knife may have some visible blood residue, but the heavy rust and poor condition makes it uncertain. It is now under secret investigation by the LAPD and currently being tested for hair and fingerprints before being sent off to look for DNA and other evidence.

The lack of a murder weapon in the Simpson trial has been a source of controversy over the years, with some sources claiming that Simpson kept the murder weapon or enlisted help to hide it. A knife salesman who was meant to testify to having sold Simpson a knife similar to the prospective murder weapon was removed after selling his story to the press.

Simpson is unlikely to be charged again for the murders of his ex-wife Nicole Simpson and Ronald Goldman because of laws that prevent someone from being tried twice for the same crime.