A Chicago judge ordered Chevazz Campbell detained Sunday after he was charged in the killing of CTA janitor Julian Mobley at the Damen Green Line station on the Near West Side. Mobley, 41, was stabbed Thursday afternoon after a confrontation at the station, prosecutors said. Campbell, 37, of Kenwood, faces charges including first-degree murder, felony murder, armed robbery and weapons offenses. The charges are allegations; he is due back in court Wednesday. Prosecutors said surveillance footage shows Campbell entering the station at 2:58 p.m. with two bags. After an argument with a station attendant, Campbell left and returned, then sprayed Mobley in the face with a chemical spray, prosecutors said. Mobley ran from the station, and Campbell chased and stabbed him once in the neck, according to the state’s account. Mobley made it to a janitor’s closet, where firefighters found him unconscious. He was taken to Stroger Hospital, where he was pronounced dead. Prosecutors said Campbell took Mobley’s work phone and personal items, then discarded some of them in a storm drain before entering a nearby market. The store owner and the station attendant later identified Campbell, prosecutors said. Campbell turned himself in at an Englewood police station Friday night. Police said he acknowledged being the person who stabbed Mobley. He was on electronic monitoring at the time, prosecutors said, and had two active arrest warrants related to earlier felony cases. In a joint statement Sunday, Cook County State’s Attorney Eileen Burke and Amalgamated Transit Union Local 308 President Pennie McCoach said Campbell had been on monitoring while on probation for a retail theft conviction. They said prosecutors had sought probation violations at least four times over alleged curfew breaches, including periods when he was out of compliance for hours. The statement criticized what Burke and McCoach called a lack of effective oversight of the county’s electronic monitoring system. McCoach said transit workers deserve to be able to do their jobs and return home safely, adding that the union had raised safety concerns for years. Mobley’s 14-year-old daughter spoke publicly after his death about losing the chance to share more years with her father and the impact on her younger brother. Mobley’s killing has renewed scrutiny of how electronic monitoring violations are tracked and addressed, as well as the safety of workers serving Chicago’s transit system.