ALEXANDRIA, Va. (WUSA) Detectives with the Alexandria Police Department are asking for the publics help in identifying a suspect wanted in a robbery that occurred in the 3400 block of Mount Vernon Avenue.Police said on July 22, a man approached a store clerk and asked to buy some cigarettes. However, when the clerk opened the cash register to give the man his change, the man climbed over the counter, took money from the register and then fled.The suspect in the…