Reproducibility of fingerprint microfeatures

Abstract

Background: Poroscopy, as a means of personal identification, is largely unexplored. The present study aims at assessing the reproducibility of fingerprint microfeatures namely, pore area, inter-distance, and angle, in fingerprints obtained on two surfaces namely, glass and sticky side of adhesive tape, for a period of ten consecutive days. As far as the authors are aware, no prior research has attempted to evaluate pore parameters on sticky side of adhesive tape. Methods: Plain-inked fingerprints of the left thumb, right thumb, and right index finger were collected on two surfaces namely, glass and sticky side of adhesive tape (using two methods) for ten consecutive days. Photomicrographs were captured and four pores, lying on the same ridge and having clear well-defined margins, were selected from the central region of each print. These specific sweat pores were used to measure the pore area, inter-distance, and angle using Image Pro® Software. Data were analyzed using Statistical Product and Service Solutions (SPSS) software version 16. One way analysis of variance (ANOVA) was carried out using “area,” “length,” and “angle” as the dependent variables. Results: Results obtained depict pore area, inter-distance, and angle to be significant (p<0.001), on all 10 days for both the surfaces. In terms of quality, better pore details were depicted by fingerprints obtained on the sticky side of adhesive tape (using procedure (iii), wherein the sticky side of adhesive tape was pressed against the inked thumb of the participant). Furthermore, the pore area was found to be non-reproducible while the pore inter-distance and angle were found to be reliable and reproducible in nature. Conclusions: Crime scene fingerprints should be first matched with specimen fingerprints on the basis of ridge characteristics. However, on occasions when sufficient number of ridge characteristics are not available for comparison, sweat pores should be employed. This study highlights the reproducibility and reliability of pore inter-distance and angle and encourages their use in fingerprint matching.