The 17-year-old Grovertown man police say robbed a Plymouth store at knifepoint will be charged as an adult. Corey Michael Sobieck is charged with armed robbery and intimidation. Both are class B felonies, and each carries a maximum of 20 years in prison. Police say Sobieck walked into the Karma Records store about 5:20 Monday evening, brandished a knife at the clerk, threatened to murder her and grabbed cash from the register. Plymouth Police apprehended him a short time later and recovered the knife in some nearby weeds. Sobieck is also on juvenile probation in Starke Circuit Court for conversion.