The handgun used to shoot dead rapper Tupac Shakur was found by police officials 19 years ago but never handed over to officers investigating his murder.
A .40 calibre Glock was discovered in 1998 and tests later revealed it was the same weapon used to kill the rapper.
It was found in the backyard of a Crips gang member, in Compton, Los Angeles, but was not transferred to police in Las Vegas, where Tupac's murder is still unsolved.
The whereabouts of the weapon is now a mystery, reports thesun.co.uk.
Records are said to show that the Los Angeles County Sheriff's Department tested the gun in 2006 and it came up as a match for the one used in Tupac's murder.
A new documentary, which unearthed paperwork showing the gun found, claims that it disappeared amid prosecutor fears that it might spark gang warfare.
The producers of "Who Killed Tupac?" say that investigators were concerned about violence breaking out given that the weapon was linked to a Crips member who had "beef" with Tupac.
Tupac was gunned down on September 7, 1996, while driving through Las Vegas.
Numerous people, including fellow rapper Notorious BIG, were implicated in his death. But the identity of his killer has remained a mystery for more than 20 years.