Valdez and the victim, who police identified as 20-year-old Luis Sanchez of Los Angeles, were reportedly working together about 1:45 p.m. at a construction site in the 4200 block of Burns Avenue when, for reasons not immediately known, they got into a dispute.
Police say Valdez used a hammer to bludgeon Sanchez's face before fleeing the scene.
Sanchez was taken to a nearby hospital, where he died an hour later, Gamble said.
A neighbor, however, reportedly got the license plate number of Sanchez's car and called police, who notified him of the crash.
Alvarez said Sanchez and Valdez then visited her home, promising to repair the SUV.