This is a kinda funny one, will spawn a ped somewhere in the map and will patroll an area, if you are NOT a police or something like it (leo), the ped will look at you and you will know that the ped is the seller, he will walk in a strange way. You can add or delete points on the server folder sconfig.lua
Admin will have a command "ilegalPed" that will mark on the map the ped, the rest of it, need to find it ;).