Abstract

Determination of the order of latent fingerprints deposition on the surface of thermal paper, often found in crime scenes, is related to the study of time course and aging of fingerprints and can provide additional information in criminal investigations. A preliminary study was performed to determine the deposition order of fingerprints left with two different conditions of deposition pressure and time (in seconds) after 1 day intervals for 7 days on thermal paper (receipt and fax thermal paper) using an iodine fuming method. The resultant images of the visualized fingerprints were analyzed with densitometric image analysis to measure the changes in the areas of the ridges, which can be correlated to the deposition order. No significant variation was found with the different types of thermal paper. The average areas of the friction ridges increased gradually or were similar to the values from day 1 for 3 days, and then a continual decrease was shown from day 4 through day 7. The area values from day 6 and day 7 were less than half of those from day 1. Furthermore, the test with overlapped fingerprints showed the possibility of differentiation between fingerprints that are 1-3 and 6- 7 days old based on the clarity visible to the naked eye. Additional experiments with the deposition conditions can prove that the current method is valuable for the determining the order of fingerprint deposition on thermal paper.