Juan Carlos Garcia, 34, was found Friday afternoon with a single gunshot wound to his head in the back of a 2003 Ford Taurus parked at Soquel High School in Soquel. He was pronounced dead at the scene.
Police believe he was killed in a different location then driven to the high school.
On Saturday, Santa Cruz County sheriff's deputies arrested Federico Lozoya Castillo in connection with Garcia's murder.
Castillo, 44, was initially contacted by sheriff's detectives for an unrelated narcotics offense. It was later determined he was involved in the sale of illegal drugs, and investigators believe Garcia was one of his customers, according to the sheriff's office.
Evidence found during the initial arrest implicates Castillo in Garcia's killing, according to the sheriff's office. A search of Castillo's home in the 4100 block of Clares Street in Capitola allegedly turned up additional evidence linking him to the murder.
Castillo had a prior homicide arrest in 1986, but he was not convicted in that case.
Castillo, who lives alone, described himself to police as self-employed and said his jobs include pool cleaning, sheriff's Sgt. Dan Campos said.
Authorities have not said whether others were involved in the murder, but Campos said he doesn't believe the community is in any danger.
An autopsy report is expected this afternoon.