What are the unique challenges of analyzing non-exit gunshot wounds in forensic science?
Executive summary
Non-exit gunshot wounds — where a projectile remains in the body or an exit defect is absent — present a constellation of forensic challenges: determining trajectory, recovering the projectile, and distinguishing entrance from exit morphology often requires integration of autopsy, radiology, and ballistics [1] [2]. Different modalities have complementary strengths and limits, and disagreements about interpretation can have profound medicolegal consequences, so a multidisciplinary, evidence-driven approach is essential [3] [4].
1. Defining the problem: what “non-exit” means and why it matters
A non-exit gunshot wound can be a retained projectile, an unidentifiable exit wound, or a case where the projectile follows an unexpected route (even through natural orifices), and each scenario complicates the basic forensic goals of establishing trajectory, range, and manner of injury [1] [5]. Those goals — determining path, identifying entrance vs. exit, and recovering a projectile — are routine objectives of forensic pathologists but become uncertain when standard wound patterns are absent or ambiguous [2] [5].
2. Morphologic ambiguities: why entrance and exit can be confused
Typical entrance wounds show circular defects with abrasion collars while exits are often irregular, but real cases deviate from textbook patterns — stellate or keyhole defects over bone, close-range blast effects, or atypical tissue response can obscure classic signs and mislead even experienced examiners [5] [6] [7]. Emergency clinicians are explicitly warned not to label wounds entrance/exit based on size alone, because surface appearance varies with tissue type, angle, and projectile behavior [8].
3. Ballistics and tissue interactions: hidden variables that defeat simple readings
Bullet mass, velocity, shape, and construction interact with tissue density, elasticity, and organs to produce complex cavitation, fragmentation, or re-entry phenomena that change wound morphology and may leave no clear external exit [9] [7] [6]. Shotgun and close-range injuries, high-velocity projectiles, and fragmenting ammunition all increase the chance of retained projectiles or multiple internal paths that complicate trajectory reconstruction and caliber attribution [7] [5].
4. Imaging and recovery: strengths and blind spots of radiology
Postmortem and clinical imaging — MDCT/PMCT and micro-CT — can localize fragments, reveal hidden channels, and sometimes show beveling in bone to indicate directionality, but CT does not replace hands-on autopsy for localizing many wound features and interpreting soft‑tissue nuance [4] [5]. Studies show PMCT outperforms autopsy for locating fragmented bullets while conventional autopsy remains superior for localizing many gunshot injuries, and micro-CT may help when textiles are damaged or missing [5] [10].
5. Forensics in the field and the courtroom: procedural and evidentiary risks
Inadequate scene documentation, premature surgical alteration of wounds, or reliance on non‑specialist clinical descriptions can destroy crucial evidence; radiographs and preoperative photographs are repeatedly recommended to preserve projectile position and wound morphology for later forensic analysis [11] [8]. Misclassification of wounds has real legal stakes — altering determinations of suicide versus homicide, or obscuring whether a shot was self-inflicted — and uncommon cases regularly require multidisciplinary re-evaluation to avoid miscarriages of justice [3].
6. Emerging tools and contested limits: AI, multidisciplinary teams, and remaining gaps
AI and image‑analysis tools show promise for classifying wounds but struggle with multiple wounds, retained projectiles, and the tactile manipulations pathologists use during autopsy; studies caution that 2D image models and current AI classifiers still miss cases the experts find challenging [12] [13]. Best practice therefore remains a combined approach — forensic pathology, ballistic analysis, advanced imaging, and careful scene/surgical documentation — while acknowledging that some cases will remain indeterminate without new evidence or technologies [3] [4].