A pointing device incorporates a biometric sensor at a location such that when
operating the pointing device in a normal manner, a user's hand rests naturally
in a position to place a finger of the user's hand in proximity to and readable
by the biometric sensor. In one embodiment, a computer trackball pointing device
includes a fingerprint sensor which is equally well suitable for use by either
a right-handed or a left-handed user. Along with positional information from a
position sensor and user selection information from at least one user-depressable
button, the pointing device also conveys to an attached computer system information
associated with the user's identity detected by the fingerprint sensor. Such a
pointing device is well suited to both transparent verification as well as continuous
verification, for if a user removes his or her hand from the natural position when
using the device, the user's fingerprint will no longer be detectable by the fingerprint
sensor, and the computer system to which the pointing device is attached can be
alerted as to the need to re-authenticate any additional attempts at using the
pointing device.