Las Vegas, Aug. 18 -- The long-running investigation into the 1996 killing of hip-hop legend Tupac Shakur moved into a courtroom Monday (local time) as witnesses testified on the first day of Duane Keith Davis' murder trial, with prosecutors describing the shooting as "an act of revenge", and the defense counsel challenging the strength of the evidence after three decades.

Davis, 63, is charged with one count of murder with a deadly weapon in connection with Shakur's death. He has pleaded not guilty, according to CNN.

Prosecutors do not allege that Davis personally fired the shots that killed Shakur. Instead, they contend that he orchestrated the drive-by shooting in retaliation for an assault on his nephew, Orlando Anderson, earlier on...