  We study the effect of growth on the fingerprints of adolescents, based on
which we suggest a simple method to adjust for growth when trying to recover a
juvenile's fingerprint in a database years later. Based on longitudinal data
sets in juveniles' criminal records, we show that growth essentially leads to
an isotropic rescaling, so that we can use the strong correlation between
growth in stature and limbs to model the growth of fingerprints proportional to
stature growth as documented in growth charts. The proposed rescaling leads to
a 72% reduction of the distances between corresponding minutiae for the data
set analyzed. These findings were corroborated by several verification tests.
In an identification test on a database containing 3.25 million right index
fingers at the Federal Criminal Police Office of Germany, the identification
error rate of 20.8% was reduced to 2.1% by rescaling. The presented method is
of striking simplicity and can easily be integrated into existing automated
fingerprint identification systems.
