Centralia police are investigating another armed robbery, this time to the Family Dollar Store on the 800 block of North Elm Street.  Officers responded to a call of an armed robbery at the store around 8:45 PM Monday.  According to police reports, a shorter black male dressed all in black and wearing a mask approached the clerk, pointed a chrome revolver at her and demanded money.  The suspect fled northbound on foot from the store with an undisclosed amount of cash.  A police K-9 tracked the suspect for about two blocks before losing the scent.  No injuries were reported. Three other recent armed robberies included the Dollar General Store in Central City, FuelVend in Centralia and Blue Goose in Wamac, which have all resulted in arrests.  Anyone with information regarding the Monday night robbery of the Family Dollar Store is urged to contact their local police.