Legendary rapper Tupac Shakur knew his assassin - but his murder remained a mystery because police didn't care to investigate, a new documentary claims. The shocking remarks are made by Tupac's friends, family and music business colleagues in the episode of Snapped: Notorious Set to air on Oxygen on September 10 - almost exactly 21 years since his death. The two-hour documentary paints a vivid picture of the night of the legend's death.. That includes interviews with those who were at the rapper's bedside as he lay dying - and indicated who his killer was. Tupac, who lost a finger in the shooting, is said in the documentary to have nodded after being asked if he knew who opened up on him with a .40-caliber Glock. But his killer was never caught nor tried for the murder, because of police inaction, his associates say. Check local listings.