Reflected near-infrared photography: Digging deeper into post-mortem examination

Abstract

Aim: This research aims to investigate the utility of the Near Infra-Red (NIR) photographic technique in visualizing forensic evidence in a post-mortem examination.

Material and methods: A total of twenty-six deceased (male: n = 15; female: n = 11) were brought to the Mortuary of King George's Medical University, Chowk, Lucknow, Uttar Pradesh, India (226003), and were used to investigate the applicability of the human visible spectrum (HVS) & near-infrared photography. In the investigation, a modified Nikon D5300 crop-framed digital single-lens reflex camera was used for NIR Photography in combination with a Micro-Nikkor 105 mm, f/2.8, (Nikon Inc., Melville, NY, USA), Hoya R72 (760nm-860nm) infrared filter and a Nikon D5600 crop-framed digital single-lens reflex camera in combination with Nikkor 50mm lens for Human Visible Spectrum (HVS) Photography.

Results: The finding of the study reported that the application of the NIR photography would be the best of the investigative techniques for visualization and photo-documentation of forensically relevant post-mortem findings, such as - trace evidences (e.g., blood spots & soil particles on dark clothing), in external findings (e.g., contusion on victim's body) also for internal findings in a road traffic accident (RTA), gunshot, and drowning victim (e.g., mud particles in the trachea of drowning victim & localizing contusion of the scalp in road traffic accident cases).

Conclusion: Human visible spectrum (HVS) photographs taken with Nikon D5600 provides substantial evidence for documentation purpose, the best results for trace evidence & contusion visualization in Post-mortem examination of the deceased were achieved with the NIR Photography in combination with indirect sunlight & room light as an infrared light source. (At a wavelength of 760nm-860nm).

Keywords: Contusion; Forensic findings; Forensic photography; Hoya R72; NIR photography; Road traffic accident.