Ivan Orozco, 19, was shot several times in the torso as he sat in a vehicle with his teenage girlfriend on Nov. 4.
Vallejo police said the murder in front of a residence in the 900 block of Cherry Street in south Vallejo happened during an attempted robbery. According to police, one of the three suspects took the girl out of the car and threw her to the ground before the shots were fired around 1:45 a.m.
Orozco had no prior contacts with police and his murder was the city's ninth in 2009, police said.
Vallejo Police Chief Robert Nichelini requested the reward.
The Governor's Reward Program has offered 294 rewards since 1967 and 22 gave been paid.
The rewards are offered after the local law enforcement agency investigating the crime requests one because all investigative leads have been pursued.