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.