Arlington police say a 29-year-old man stabbed his ex-girlfriend to death last year, then set a fire in the apartment that killed their 1-year-old son.Thomas Olivas was arrested Monday evening at a sports bar in Hurst by the Arlington Police Department Fugitive Unit and the U.S. Marshals Dallas/Fort Worth Fugitive Apprehension Strike Team.Firefighters discovered the bodies of Mechelle Gandy and her son, Asher Olivas, on March 20, 2011, after a fire tore through their home at Presidents Corner apartments in Arlington.Investigators with the Tarrant County medical examiners Office concluded that Gandy, 26, died from multiple stab wounds. Asher Olivas died from burns from the fire.Shortly after the fire, detectives began looking into Thomas Olivas' involvement in the deaths and gathering evidence, said Tiara Richard, spokeswoman for the Arlington Police Department.Olivas and Gandy had been arguing over issues of child support for their toddler son, Richard said. Gandy worked at 7-Eleven and Pluckers restaurant.Olivas, who lives in Bedford, is awaiting a capital murder charge in the Arlington City Jail. Bail was set at $1 million."This is one of those cases our detectives were anxious about bringing to a resolution for the sake of this woman and the childs family," Richard said. "To have someone in custody is the first step toward justice."