Can dorsal knuckle creases facilitate human identification in forensic medicine? A pilot study

Abstract

Introduction: In many forensic investigations into cases of cyberbullying and online violence against minors, video footage can serve as crucial evidence, as it allows the identification of the perpetrator's physical features. Although the face is often concealed, other parts of the body are frequently exposed and can be revealing. Objective: This study analyzes the horizontal linear folds (HLFs) on the dorsal aspect of the proximal interphalangeal joint (PIPJ) of the dorsum of the hands as a unique anatomical feature for human identification with legal value in forensic medicine. Material and methods: Real and ideal scenarios were performed to obtain doubtful and doubtless images of the dorsal hands by a webcam and a high-resolution camera, respectively. The presence and number of HLF from 112 dorsal PIPJs (4 fingers, 2 hands, 14 individuals) were quantified and statistically compared by analyzing the similarity between sample groups using Sorensen-Dice coefficient and Jaccard index. Results: HLF resulted in a sensitivity (positive identification) of 78.57%, but a specificity (negative identification) of 26.1% (area under ROC curve = 55.3%). Visual inspection of doubtful and doubtless samples achieved a 100% match in human identification. Conclusions: The morphological variability and unique pattern of the HLF can be used as a simplified method to delimit human identification in forensic medicine.