Authorities in Chicago said a suspect in a $17,000 Radio Shack robbery was tracked down through a GPS device that was part of the loot. Authorities said Raymond Jefferson, 20, who was wielding a handgun, and two unarmed accomplices tied up workers and customers at the store Friday and took items that included cellphones, iPads, Kindles and a GPS device. Jefferson was arrested about 2 hours after the crime by officers who located him through the stolen GPS unit. Jefferson, who was identified by witnesses, was charged with armed robbery and aggravated kidnapping. He was ordered held on $350,000 bail.