Gallegos, who stabbed Dustin Hoffman in the chest during the brawl on Nov. 11, 2012, could spend up to life in prison.
Prosecutors have said that Gallegos was wielding a knife when he fought several people in the parking lot outside the Southern X-Posure club, 3420 S. State St.
Witnesses reported seeing him attack Hoffman, who stumbled away, chest covered in blood, and fell to the ground.
When security and bouncers intervened in the fight, witnesses said, Gallegos stabbed one of the bouncers in the side before stabbing Hoffman.
Hoffman, of Bakersfield, Calif., died in the parking lot.
The autopsy determined he suffered two stab wounds, one to the chest that punctured his heart and a second to the right side of his rib cage that punctured his lung.
The bouncer was taken to the hospital in with a punctured liver and lung.
Police later found a long-sleeved button-up shirt and white undershirt inside two garbage bags in the Dumpsters at Gallegos' apartment at 3687 S. West Temple, according to court documents.
The torn shirts match the description of what the attacker was wearing, and the long-sleeved shirt had a reddish brown stain consistent with blood, charges state.
Gallegos, who was a prison parolee at the time of his arrest in the 2012 murder, has a long criminal history, with court records showing convictions including one for aggravated robbery, a first-degree felony.
He has been in custody since his arrest.