RESUMEN
Fingermark ridge drift is a random modification of (aged) fingermark patterns at a ridge scale. This phenomenon was previously proven to alter key elements used for identifications, such as the appearance of minutiae. Little is currently reported on the underlying factors contributing to its occurrence. The present study was designed to investigate further the variables of a previous study by including a total of 768 fingermarks from a male and female, two substrates (glazed ceramic tile and plastic), two distinct color powder developers (carbon black and titanium dioxide), three indoor lighting conditions (direct natural light, shade, and darkness), and two secretion types (sebaceous- and eccrine-rich). Fingermarks were aged for 2-72 days, powdered, photographed, and drift detected by three independent observers. All aged fingermarks (672) were compared relative to fresh fingermarks (96), and ridge drift was observed in 42 of 672 (6%) fingermarks, while 168 (25%) were reported as indeterminate results. While ridge drift was detected in multiple fingermarks across all independent variables, statistical analysis using a multinomial logistics model showed that only powder type, secretion type, and the substrate indicated a significant correlation with increased incidences of this phenomenon. There was no significant correlation with the donor, time since deposition, or the environmental lighting conditions used. The highest incidence occurred when carbon black powder was used on a plastic substrate (>10%). The average observation of ridge drift is 6% of samples supporting that this phenomenon is not a rare event, particularly considering the conservative analysis approach implemented.
Asunto(s)
Dermatoglifia , Adulto , Colorantes , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Polvos , Factores de TiempoRESUMEN
Morphological changes in the width of latent fingermark ridges occur naturally over time. This could be used to examine the aging process of latents and eventually estimate time of deposition. In a crime context, it is common practice to compare a questioned (aged) fingermark with a database of known (inked) prints. Therefore, in the absence of fresh fingermarks for aging purposes, it is of interest to reveal correlations between these two categories of fingerprints with regard to the widths of their ridges. The present study explores correlations of ridge widths between flat and rolled inked prints with latent fingermarks visualized with carbon black (CB) and titanium dioxide (TiO2 )-based powders among a small population of ten donors. Results revealed consistent differences between the ridge widths of latent and inked prints as well as flat and rolled impressions. Latent fingermarks visualized with CB and TiO2 powders showed ridges with comparable widths.