Background: The goal of this study was to investigate the usefulness of various photographic techniques in visualizing previous tattoos under cover-up tattoos.
Material and methods: Ten volunteers with 11 known cover-up tattoos were examined using different photographic techniques: A Canon EOS 6D full-frame digital single-lens reflex camera used in conjunction with a SB600 off-camera flash system and an extension cord; and a Leica M8 digital imaging system camera in conjunction with two different infrared filters (715 nm and 850 nm) and a Metz CL-45 handle-mount flash. A Lumatec Superlite 400 forensic light source was used along with the Canon EOS 6D as a third system.
Results: The best results for black cover-up tattoos were achieved with the full-frame digital single-lens reflex camera in conjunction with the off-camera flash system and, for colored cover-up tattoos, with IR-photography at a wavelength of 850 nm. The Lumatec Superlite 400 light source did not provide better results for conventional photography than those obtained with flash lighting.
Discussion: In nine out of eleven cover-up tattoos, the previous tattoos could, at least, be partially visualized. The quality of the visualization depended on the color, pattern, density, and quality of the cover-up tattoo as well as on the photographic technique. None of the examined photographic techniques could satisfactorily image the previous tattoo if the cover-up tattoo was large and black, especially not if it was densely inked.
Conclusion: Depending on the color of the cover-up tattoo, a full-frame digital single-lens reflex camera in conjunction with a SB600 off-camera flash system (for black cover-ups) or infrared photography with flash lighting and an 850 nm filter (for colored cover-ups) proved to be the best of the investigated techniques to visualize a previous tattoo under a cover-up tattoo.
Keywords: Cover-up tattoo; Forensic light source; Forensic photography; IR photography; Identification; Lumatec Superlite 400.