Enhancing foundational validity of forensic findings in nonlethal medico-legal strangulation examinations

Abstract

Background

Nonlethal strangulation occurs when the brain is deprived of oxygen because of external compression leading to the occlusion of the neck's blood vessels and/or airway. The current state of strangulation science confines expert testimony to merely describing injuries attributed to strangulation ‘based on the expert's experience and training.’ Expert testimony that can quantify the likelihood that observed injuries are attributable to strangulation would strengthen the scientific validity of such testimony.

Purpose

This study aims to identify those documented features, or clusters of features, that are associated with cases where strangulation is reported versus cases where strangulation is not reported. Methods: This study is a retrospective analysis of medical record data from patients seeking forensic examinations for strangulation and/or sexual assault who presented to the emergency department of an academic medical center from January 2018 to June 2022.

Results

Among the 170 cases, 77 were documented as strangulation-absent and 93 were documented as strangulation-present. A simple classification algorithm was developed to identify these cases where strangulation was present. Prominent features of this algorithm included: presence of petechiae, observed number of injuries around the mouth, face, head and neck, and total number of injuries. This algorithm has a false positive rate of 5 % and a false negative rate of 32 %.

Discussion

To our knowledge, this is the first medico-legal research study to produce an algorithm to assist with classifying cases of strangulation given specific forensic examination characteristics. The study demonstrates the value of data collection in medico-legal research for developing an algorithm that enables forensic examiners to use data-driven methods to verify victims’ reports of strangulation.