Original Ultraviolet Light posting: September 17, 2023

Updated: November 23, 2024

The use of an alternate light source (ALS), specifically ultraviolet (UV) light with a wavelength under 490nm, should be considered as a tool during searches for human remains [2].

Recent applications during HRD searches in Virginia by Search and Rescue Tracking Institute (SARTI) members have found the use of ALS with wavelengths in the 385-395nm range to be very effective.

A study by Thompson, O. L., Simmons, T., Russell, J. A., Stockman, S., & Swall, J. (2024) titled Assessing the effectiveness of alternative light sources in search for skeletal remains found that ALS with the wavelength between 395 and 425 nm produced the most productive results in the detection of skeletal remains.

Collagen, an organic protein found in bone, is responsible for the fluorescent properties of animal bones. According to Tzaphlidou [3], collagen represents more than 90% of the organic matrix in bone. This fluorescent property degrades over time, but may be visible for approximately 200+ years. Forensic cases less than 50 years should benefit from the use of UV light to observe bone's fluorescent properties.

Factors that could affect a bone's fluorescent properties include heat, pH, ultraviolet radiation, and moisture. 

According to a study by Gallant [1], remains that have been exposed to fire could not be differentiated from their surroundings using UV light. 

Search and Rescue Tracking Institute (SARTI) began utilizing UV light technology to search for human remains on October 26, 2023 in Virginia. Searchers utilized 365nm, 385-395nm, and 390nm wavelength UV handheld ALS. This search produced successful results as searchers discovered 10 additional human bones. Since that time, SARTI has continued to deploy UV ALS with successful results on 11 searches across the Commonwealth of Virginia and continues to advance the science of ultraviolet light for the detection of human remains.

Experimentation Results Using UV Light vs. White Light at Night

Additional examples of animal bones when exposed to ultraviolet light

Effects of Distance

Human Teeth

Note that the roots fluoresce more than the enamel

Note: Unless otherwise noted, the UV light photos above were utilizing a Gearlight UV black light flashlight S100 with an ultraviolet wavelength of 390nm. #ad

References:

1. Gallant A. Alternate light sources in the detection of bone after an accelerated fire: a pilot study. J Forensic Sci 2013;58(S1):S221-6.

2. Swaraldahab, Mohamed A.H. , Christensen, Angie M. The Effect of Time on Bone Flourescence Implications for Using Alternate Light Sources to Search for Skeletal Remains. J Forensic Sci, Marck 2016, Vol. 61, No. 2.

3. Tzaphlidou M. Bone architecture: collagen structure and calcium/phosphorus maps. J Biol Phys. 2008 Apr;34(1-2):39-49. doi: 10.1007/s10867-008-9115-y. Epub 2008 Oct 15. PMID: 19669491; PMCID: PMC2577747.

4. Thompson, O. L., Simmons, T., Russell, J. A., Stockman, S., & Swall, J. (2024). Assessing the effectiveness of alternative light sources in search for skeletal remains (Master’s thesis, Virginia Commonwealth University). Department of Forensic Science, Virginia Commonwealth University.

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Luminescence of thermally altered human skeletal remains

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