Tucson police are looking for a suspect in the armed robbery of a convenience store last month who was caught on a security camera. The suspect is described as an 18- to 23-year-old man, standing 5-feet-7-inches tall and weighing between 140 and 160 pounds. At about 2:45 p.m. Jan. 9 he robbed a Circle K at 4160 N. First Ave. The suspect was wearing a black, hooded sweatshirt, plaid shorts and a yellow-brimmed baseball cap when he approached the cashier and demanded cash. The suspect had his hands in the pockets of his sweatshirt and implied he had a weapon.