Mr Davis has long acknowledged his involvement in the killing, boasting he was the "on-site commander" in the effort to kill Shakur and Death Row Records boss Marion "Suge" Knight in revenge for an assault on his nephew.
Under Nevada law, anyone who aids or abets a murder can be charged with the killing, in the same way that a getaway driver can be charged with bank robbery even if he never entered the bank.
Tupac Shakur, was a best-selling hip-hop artist releasing hits such as 'Changes', 'Dear Mama', and 'California Love'. He was a major star in the world of rap when he was killed at the age of 25.
He was signed to Death Row Records, an outfit associated at the time with Los Angeles street gang Mob Piru, which had a long-standing feud with the South Side Compton Crips - a group in which Mr Davis was a key figure.
Prosecutors said last month that what happened on the night of the killing had been largely understood for many years, but they had not had sufficient admissible evidence to advance the case.
That began to change when Mr Davis, reportedly the only person in the car that night still alive, published an autobiography and spoke about the crime for a TV show.
