Abstract: A fraud-proof identification system is provided with a point-to-point in focus imaging system preferably a line tracking arrangement for imaging skin profiles particularly of the thumb-top which contains relatively many continuous lines and avoids mental association with criminal finger print actions. Characteristics from skin profiles, preferably mutual line distances progressively measured along a selected skin line are compared with such information stocked in the system in order to discriminate upon authorization. A line tracking system is preferably provided with a servo-mechanism, a control signal of which acting as measuring signal.