Methodology for Retrospective Blood Alcohol Threshold Assessment under Uncertainty

Juan M. Rodriguez Diaz, University of Salamanca

Co-authors: Maria Teresa Santos-Martin, University of Salamanca; Irene Mariñas-Collado, University of Oviedo

Abstract: Estimating past blood alcohol concentration (BAC) is a complex forensic challenge, particularly when the timing and quantity of alcohol consumption are uncertain. Traditional methods, such as the Widmark equation, assume constant elimination rates but are inadequate during alcohol absorption or in complex intake scenarios. This study extends a simplified Gamma model by incorporating a probabilistic framework to account for ingestion time uncertainty. A sigmoidal function smooths the absorption curve, aligning it with physiological processes. This approach estimates expected BAC values and evaluates the probability of exceeding legal thresholds at earlier times, enhancing accuracy and interpretability in forensic investigations.