It utilizes the ability of a strain of Acinetobacter calcoaceticus, which was isolated during the course of this work, to proliferate on the material present in a print deposit. When the bacteria are brought into contact with a print, under the appropriate conditions, they multiply and form colonies on the ridges. As a result of this growth, the characteristic fingerprint pattern becomes apparent. Methods for the selection of the bacterial species are described, and details of the procedures employed for the development of latent prints are given. (Publisher abstract)