A 23-year-old Philadelphia police officer was charged Wednesday with selling heroin to a confidential informant working for the FBI.Jonathan Garcia, who has been on the force for three years and is stationed in South Philly's 17th district, was charged with four counts of distribution of heroin and two counts of carrying a firearm during drug trafficking. Garcia, who was arrested at his home Tuesday night, pleaded not guilty Wednesday in his arraignment before federal Magistrate Timothy Rice. He is being held at the Federal Detention Center in Center City pending his bail hearing on Friday.