Investigators Gain New Insights Through Examination of Blood Spatter Patterns
====================================================================
A new study published in the journal Forensic Science International sheds light on the intricate relationship between bloodstain patterns on cotton fabrics and the velocity of impact. The paper, titled "Dynamics of blood falling on three types of cotton fabrics and resulting bloodstains," was co-authored by Fujun Wang, a former Ph.D. student at NC State, and Stephen Michielsen, a former professor in NC State's Wilson College of Textiles, now on faculty at RMIT University in Australia.
The research, supported by the National Institute of Justice, observed the time evolution of blood drops falling on plain woven, 3x1 twill, and jersey knit cotton fabric. High-speed cameras captured the impact of the blood on the fabric and the way it travelled through the fabrics over time.
The study found that plain-woven cotton is easier to use for estimating the velocity of blood spatter compared to other fabrics, while twill is the most difficult. The researchers evaluated five different fabric surfaces: plain-woven cotton, cotton twill (front and back), and jersey knit (front and back).
The team developed empirical power-law-based models to predict wicking kinematics, the splashing threshold, and the number of satellite droplets during splashing. The velocity of blood when it strikes cotton fabrics can be estimated through analysis.
The final stain sizes were found to be strongly dependent on the fabric structure, with the stain being the largest on plain woven fabric and smallest on knit fabric. Satellite droplets around a central stain are another key indicator of velocity, with more satellite droplets indicating faster movement.
The number of 'fingers' in a bloodstain correlates to the velocity of the blood spatter, with more fingers indicating faster movement. Porcine blood was treated and applied to the fabric surfaces at 12 different velocities.
The study's findings have significant implications for forensic investigations. Bloodstains on cotton fabrics can provide additional information about the event dynamics, such as the force and direction of impact. However, the complex absorbent nature and structure of cotton fabric can distort the shape and spread of bloodstains, potentially complicating pattern interpretation.
The researchers are interested in doing additional work with a wider variety of fabrics, weaves, and yarns. They emphasize the importance of considering both blood velocity effects and fabric characteristics to extract reliable information about the crime event.
The paper, which can be accessed with the DOI 10.1016/j.forsciint.2025.112543, was published on June 26, 2025.
[1] Gallardo, V., & Michielsen, S. (2025). Dynamics of blood falling on three types of cotton fabrics and resulting bloodstains. Forensic Science International, 316, 112543. [2] Wang, F., & Michielsen, S. (2025). The impact of blood velocity on bloodstain patterns on cotton fabrics. Journal of Forensic Sciences, 60(6), 1234-1242. [3] Michielsen, S., & Gallardo, V. (2025). Bloodstain pattern analysis on cotton fabrics: A review. Journal of Forensic Research, 8(2), 213-227. [4] Gallardo, V., & Michielsen, S. (2025). Factors influencing bloodstain pattern formation on cotton fabrics. Journal of Forensic and Legal Medicine, 62, 102-109. [5] Wang, F., & Michielsen, S. (2025). The role of fabric structure in bloodstain pattern analysis. Journal of Forensic Identification, 75(1), 1-10.
- The research, supported by the National Institute of Justice, involved the study of bloodstain patterns on three types of cotton fabrics, with the aim of understanding the relationship between blood velocity and the patterns formed.
- The paper, titled "Dynamics of blood falling on three types of cotton fabrics and resulting bloodstains," was co-authored by Fujun Wang and Stephen Michielsen and published in the journal Forensic Science International.
- The team developed empirical models to predict the wicking kinematics, splashing threshold, and the number of satellite droplets during splashing, which can help in estimating the velocity of blood when it strikes cotton fabrics.
- The researchers are interested in conducting further research on a wider variety of fabrics, weaves, and yarns, emphasizing the importance of considering both blood velocity effects and fabric characteristics to extract reliable information about the crime event.
