FAIRFIELD, Calif. -- Two suspects were arrested Saturday in the fatal shooting of a Fairfield councilman who police believe may have been mistakenly killed during a drug deal.

Gene Allen Combs, 45, of Suisun City and Nicole Stewart, 33, of Fairfield were booked into Solano County Jail on suspicion of murder and use of a firearm, Police Chief Kenton Rainey announced at a news conference.

Police still were searching for a third suspect, 32-year-old convicted felon Henry Don Williams, in the death of 22-year-old Councilman Matt Garcia.

Williams' car was found in Berkeley and is being investigated, police said.

Garcia, one the state’s youngest elected officials, was shot in the back of the head the night of Sept. 1 as he stepped out of his car outside a friend’s home in the Cordelia section of Fairfield. He died four days later after he was taken off life support at John Muir Medical Center in Walnut Creek.

Fairfield police said the suspects had been in the neighborhood trying to collect a drug debt, while Garcia talked to his friend nearby.

Combs, an auto mechanic, was a passenger in a car driven by Stewart, investigators said.

“Another passenger exited the car, then shot and killed victim Matt Garcia,” police wrote in a statement of probable cause for Combs’ arrest. “After the shooting, suspect Combs left the shooting scene with the shooter and failed to contact the police.”

There’s no evidence to suggest that Garcia was actually involved in any drug deal, said acting police Capt. Darrin Moody.

Police declined to discuss further details of the shooting.

Garcia was only 21 when he was elected to a four-year term in November, becoming the youngest council member in the history of Fairfield.

Fairfield Mayor Harry T. Price said that he will continue to ask City Council to match the reward money being offered for the arrest and convictions of those responsible for Garcia's killing.

Price is requesting $50,000, which would bring the total reward money to $150,000, because the third suspect, Williams, is still on the loose.

The Fairfield City Council will also appoint someone to the vacant seat left by Garcia by Oct. 2.

Officials said that so far 22 people have picked up applications for the job.