1. A method of detecting an intrusion condition of a vehicle having an occupant compartment partially defined by an outer structure of the vehicle, said method comprising the steps of: actuating an illuminator having a limited field of illumination extending within the vehicle occupant compartment adjacent the vehicle outer structure; actuating an imager that has a field of view that substantially coincides with the field of illumination of the illuminator; creating a first image of objects in the field of illumination when the illuminator is actuated; creating a second image of objects in the field of illumination when the illuminator is not actuated; subtracting the first image from the second image to establish a sample image; determining the existence of an intrusion condition of the vehicle on the basis of a comparison of at least two sample images.