Wilfredo "Flaco" Reyes, 31, appeared before a judge in San Francisco Friday afternoon. Television cameras were not allowed to show his face.
Reyes is being charged with three counts of murder, one of attempted murder, and conspiracy.
The district attorney maintains Reyes was in the car with Edwin Ramos when he gunned down Tony Bologna and his two sons in 2008.
Ramos has been convicted of the murders. Reyes is being held on $5 million bail, he will be arraigned Tuesday.