Crime Light Imaging (CLI): A Novel Sensor for Stand-Off Detection and Localization of Forensic Traces

Abstract

Stand-off detection of latent traces avoids the scene alteration that might occur during close inspection by handheld forensic lights. Here, we describe a novel sensor, named Crime Light Imaging (CLI), designed to perform high-resolution photography of targets at a distance of 2–10 m and to visualize some common latent traces. CLI is based on four high-power illumination LEDs and one color CMOS camera with a motorized objective plus frontal filters; the LEDs and camera could be synchronized to obtain short-exposure images weakly dependent on the ambient light. The sensor is integrated into a motorized platform, providing the target scanning and necessary information for 3D scene reconstruction. The whole system is portable and equipped with a user-friendly interface. The preliminary tests of CLI on fingerprints at distance of 7 m showed an excellent image resolution and drastic contrast enhancement under green LED light. At the same distance, a small (1 µL) blood droplet on black tissue was captured by CLI under NIR LED, while a trace from 15 µL semen on white cotton became visible under UV LED illumination. These results represent the first demonstration of true stand-off photography of latent traces, thus opening the way for a completely new approach in crime scene forensic examination.

A Novel LIBS Sensor for Sample Examinations on a Crime Scene

“…In this work, we present a novel LIBS prototype, developed to fill some of the existent instrumental gaps and projected to satisfy user requirements identified by law enforcement agencies (LEAs) involved in the Real-time on-site forenSic tracE qualificatioN (RISEN) project. The RISEN system aims at supporting crime scene investigations through the acquisition of an interactive 3D model of a crime scene, which also displays the results of trace analysis obtained by various on-site contactless sensors [ 41 ]; among them is another tool developed by ENEA, namely the Crime Light Imaging (CLI) sensor for stand-off photography of latent traces [ 42 ]. Here, we also report the results of the LIBS instrument testing aimed to optimize the acquisition parameters, estimate the limits of detection (LODs) for each element, and show the instrument capability to analyze some common trace samples, as well as to identify various sample layers during the depth profiling of paints and coated plastics.…”