A 3D-printed portable episcopic coaxial illumination device for fingermark enhancement at crime scenes

Crime scene investigators have limited non-destructive optical techniques available for use at scenes for fingermark enhancement on flat and reflective surfaces, such as glass, metal and plastic. If standard optical techniques, such as diffused reflection photography, fail, investigators are generally left to employ destructive techniques, including the application of fingerprint powders or chemical reagents. Episcopic Coaxial Illumination (ECI) is an alternate optical technique for flat, reflective surfaces that produces a contrasting dark fingermark impression against a light background without the need for physical or chemical treatments. ECI is a common technique employed in laboratory settings and, although commercial portable ECI devices have recently become available, they are not designed for use with generic photographic equipment that is carried by crime scene officers as part of their standard kit. This research developed a portable and cost-effective ECI device that is 3D-printed and can be attached to any camera lens. The portable ECI (pECI) device was evaluated in a proof-of-concept, pseudo-operational environment, where the pECI was compared to conventional diffused reflection photography by photographing latent finger-marks and white powdered fingermarks. Overall, the pECI was able to record the same or more ridge detail compared to conventional diffused reflection photography on a range of pseudo-operational substrates. The pECI device therefore shows promise for enhancing fingermarks on non-porous surfaces at crime scenes and should be considered alongside routine diffused reflection enhancement. The developed pECI device can not only be used at routine crime scenes, but also in a laboratory environment, allowing flexibility in operation.