Rosanne Hughes with the Bexar County Sheriff's Office said Sunday that Joshua Manuel Lopez faces a charge of capital murder of a police officer in the killing of Elmendorf Police Chief Michael Pimentel.
Pimentel was shot while making a stop Saturday to serve an active misdemeanor warrant for graffiti. He was struck in the shoulder and abdomen and pronounced dead at a hospital.
Hughes says investigators are looking into Lopez's background.
Lopez remained in the Bexar County Adult Detention Center on a $1 million bond Sunday. Information about whether he has an attorney was unavailable.
Elmendorf has around 1,500 residents and is about 25 miles southeast of San Antonio.