1. A method in a computer system for individualizing a heartbeat signal for use as a biometric marker comprising the steps of: acquiring a plurality of electronic heartbeat signals from an individual in an electronic signal form; for each electronic signal, measuring, a plurality of pre-selected features; for each of said features, calculating the measurement's average; subtracting the measurement's average from each of the measurements to yield a centroid value; calculating a standard deviation of each measurement; dividing the centroid value by the standard deviation for each measurement to give a quotient value; and calculating the probability of divergence of each measurement using the quotient value in a T-distribution analysis.