Time-dependent morphological changes in bloodstains on tile and vinyl flooring

Abstract

Background: Estimating the age of bloodstains is a prime aspect of forensic science for reconstructing the timeline of events at crime scenes. Surface material plays a crucial role in pointing out the approximate age of the bloodstains. This study investigates the morphological changes of bloodstains on tile and vinyl flooring over 120 h. Results: Blood samples were drawn in EDTA tubes and were dropped from a height of 55 cm onto clean tile and vinyl surfaces using a micro-drip infusion set to ensure consistent droplet volume. Observations were made at specific time intervals: 5 min, 1, 2, 4, 8, 12, 24, 48, 72, 96, and 120 h, using stereo microscopy and high-resolution imaging under LED lighting. Quantitative parameters, including contact angle, diameter, and red intensity, were measured to assess the aging process of the stains. The Mann–Whitney U test indicated significant differences between the two substrates. Conclusion: This study demonstrates that the aging patterns of bloodstains differ significantly between tile and vinyl flooring, allowing estimation of bloodstain age with an accuracy of approximately ± 0.3 days over 5 days. These findings enhance the precision of bloodstain pattern analysis and offer practical tools for forensic investigations across various surface types.