Trinidad Tavarez had been working as a handyman and security guard at the Oasis Christian Church for the past year. He was living out of his van parked on the church property, police said.
Investigators say Tavarez sexually assaulted a 4-year-old girl at a church service on Father's Day.
He was arrested and booked on child molestation charges.
Tavarez has prior arrests -- one was for soliciting an undercover officer for sex.
Santa Ana detectives believe there may be more victims. They asked anyone with information to call Corporal R. Bonilla at (714)245-8412 or provide anonymous information to Orange County Crime Stoppers at (855)TIP-OCCS.