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

Area of Science:

• Forensic Science
• Optical Engineering
• Imaging Technology

Background:

• Traditional forensic methods often require close-up examination, risking alteration of delicate latent traces.
• Stand-off detection offers a non-intrusive alternative for preserving crime scene integrity.

Purpose of the Study:

• To introduce a novel sensor system, Crime Light Imaging (CLI), for high-resolution, stand-off detection of latent forensic traces.
• To demonstrate the capability of CLI to visualize various latent evidence types at distances of 2-10 meters.

Main Methods:

• Development of CLI, a portable system integrating high-power LEDs (green, NIR, UV) and a synchronized CMOS camera with a motorized objective.
• Implementation of a motorized platform for target scanning and 3D scene reconstruction.
• Synchronization of LEDs and camera for short-exposure, ambient-light-independent imaging.

Main Results:

• CLI achieved excellent image resolution and contrast enhancement for fingerprints at 7 meters using green LED.
• Detection of a 1 µL blood droplet on black tissue at 7 meters with NIR LED.
• Visualization of a 15 µL semen trace on white cotton using UV LED illumination at 7 meters.

Conclusions:

• CLI represents the first true stand-off photography system for latent forensic traces.
• This technology offers a novel, non-contact approach for comprehensive crime scene examination.
• CLI has the potential to significantly advance forensic investigation techniques.