Police say a 15-year-old boy who was killed in Des Moines was attempting to rob the 21-year-old man who shot him. Police said Thursday (11/11) that another 15-year-old boy who also was involved in the attempted robbery has been charged with one count of first-degree robbery. Authorities are attempting to have him tried as an adult. The shooting occurred Sunday morning (11/7), and the boy who was shot died Tuesday (11/9) at a local hospital. Police said Thursday that the teenager who died was armed with a handgun and the other teenager was armed with a knife when they attempted to rob the man, and he fired a shot.