Use of an Alternative Light Source to Assess Strangulation Victims

Abstract

Alternative light sources (ALSs) are commonly used at crime scenes and in forensic laboratories to collect evidence such as latent fingerprints, body fluids, hair, and fibers. This article describes the use of this technology to reveal soft tissue injuries that are not visible to the naked or unaided eye in patients who report strangulation. The value of this information to the medical, nursing, and judicial systems is discussed. The records of the 172 strangulation patients seen in our forensic nurse examiner program between 2009 and 2010 were reviewed. The SPEX Crimescope (SPEX Forensics, Edison, New Jersey) was used during the assessment of all of them. Ninety-three percent of the patients had no visible evidence of external injuries on physical examination. The ALS revealed positive findings of intradermal injuries in 98% of that group. Information obtained with ALS devices helps medical and nursing practitioners understand the gravity of patients' injuries, influences medical treatment decisions and follow-up care, and supports the prosecution of the perpetrators of crimes of violence. Educational programs about the application of ALS and the interpretation of its findings are valuable for medical, nursing, and other forensic disciplines.

Detection of Inflicted Bruises by Alternate Light: Results of a Randomized Controlled Trial

“…Gross observation of light absorption by these molecules requires the use of alternate light, specific wavelengths which may include the visible (400-700 nm) or long ultraviolet (290-400 nm) spectrums (19). Generally, light is reflected, transmitted, scattered, and/or absorbed by the skin's surface (20,21) Transmitted light can be absorbed and reflected by deeper structures, with longer wavelengths generally having greater skin penetration (20). Filters (e.g., colored goggles and camera lenses) can then be used to block the reflected light allowing the absorbed light to appear darker by comparison (19).…”

“…An alternate light source (ALS) has been suggested by the U.S. Department of Justice as a tool to assist in identifying evidence of "subtle injury" (22). However, prior research on whether an ALS is effective at clinically detecting bruising within the visible and ultraviolet spectrums is limited (21,(23)(24)(25). The few available studies have found use of an ALS enhanced bruise observation, but researchers were unable to control for the potential effects of false positives either through study design (21,24,25) or execution (23).…”

“…However, prior research on whether an ALS is effective at clinically detecting bruising within the visible and ultraviolet spectrums is limited (21,(23)(24)(25). The few available studies have found use of an ALS enhanced bruise observation, but researchers were unable to control for the potential effects of false positives either through study design (21,24,25) or execution (23). Confounding factors, such as preexisting skin conditions and topical products, could mimic bruising by producing absorption under alternate light (21,26,27).…”

Strangulation Forensic Examination

“…The study found that 93% of the victims had no visible evidence of external injuries upon examination without the ALS. Once the ALS was used, intradermal injuries were found in 98% of those patients (Holbrook & Jackson, 2013).…”

Alternate Light Source Findings of Common Topical Products

“…Alternate light and its ability to aid in visualization of sub-dermal bruises, visible and invisible to the naked eye has been examined in a small number of previous studies (Holbrook & Jackson, 2013;Limmen et al, 2013;Lombardi, Canter, Patrick, & Altman, 2015). None of these examined whether commonly used topical products absorb under various wavelengths of light.…”