An anti-theft system, especially in the form of an access and/or starting system for a vehicle has a vehicle-mounted receiver for receiving a request signal containing the instruction to find out whether objects that are associated with the vehicle, e.g. lost identifiers, are located in specific areas of the vehicle. The anti-theft system further has a vehicle-mounted control and evaluation unit for verifying whether the objects are in the specific areas of the vehicle and outputting information on whether an object that is associated with the vehicle has been found. The anti-theft system finally has a vehicle-mounted transmitter for transmitting a result signal containing the information on whether objects have been found. Such an anti-theft system allows an identifier, for example, which is associated with a user, to start a search from a distance in order to verify whether certain objects are located near or inside the vehicle.