AceShowbiz -

Even after two decades, Tupac Shakur's murder remained to be a cold case. The murder case of the "Dear Mama" rapper, who was gunned down in Las Vegas in 1996, remained a mystery until it was recently revealed that the handgun used to kill Pac had been found by the police.

According to a police document obtained by producers of A&E's docu-series "Who Killed Tupac?", the gun, which was described as "a 40 caliber Glock," was found by a citizen in a backyard in Compton two years after the murder. The weapon was later reported to police and the police filed it as a found property in May 1998.

Later in 2000, L.A. County Sheriff's Dept. took over law enforcement of Compton and 3,800 confiscated firearms, including that Glock, were transferred to the LASD. Deputy T. Brennan, who's been working on the murder of Pac's nemesis Notorious B.I.G., later spotted the address where the weapon was originally found as the residence of a well-known Crip member's girlfriend in 2006. According to the document, the Crip member was known to have beef with Pac.

Following the discovery, Brennan ordered ballistic testing and the results came back positive as a match for the gun which was used to shoot Pac to death.

While it seemed like everything got clearer for Pac's murder case, things got in the way. Federal prosecutors stopped its transfer back to Las Vegas police, out of fear that the weapon's discovery might tip off any conspirators involved in the rapper's death. TMZ suggested that should the investigation move forward, it might evoke gang violence if it came out a Crip was tied to the star's murder.

As if the gun discovery was not surprising enough, Tupac's brother, Mopreme Shakur, claimed that he had no idea that a gun which was presumably related to Pac's murder was discovered, let alone the fact that it was tested positive as the gun behind his brother's death.

"Who Killed Tupac?" airs its finale on Tuesday, December 19 at 10 P.M. on A&E.