Elk Grove resident James Cage, 26, was arrested Monday on suspicion of playing a role in Barron's death, which police said appears to be gang-related.
Another suspect in the homicide, 18-year-old Darryl Jackson, was arrested earlier.
Police were called to 6626 Valley Hi Drive at 10:19 p.m. on March 9 after receiving a report that shots had been fired.
Upon arrival, officers found Barron sitting in the driver's seat of a parked vehicle. He was pronounced dead at the scene, officials said.