tions are difficult or impossible.135,136 Workshops teach the fundamentals of basic pattern formation and are not a substitute for experience and experimentation when applying knowledge to crime reconstruction.137 Such workshops are more aptly applicable for the investigator who needs to recognize the importance of these patterns so that he or she may enlist the services of a qualified expert. These courses also are helpful for attorneys who encounter these patterns in the course of preparing a case or when preparing to present testimony in court.

Although there is a professional society of bloodstain pattern analysts, the two organizations that have or recommend qualifications are the IAI and the Scientific Working Group on Bloodstain Pattern Analysis (SWGSTAIN). SWGSTAIN’s suggested requirements for practicing bloodstain pattern analysis are outwardly impressive, as are IAI’s 240 hours of course instruction. But the IAI has no educational requirements for certification in bloodstain pattern analysis.138 This emphasis on experience over scientific foundations seems misguided, given the importance of rigorous and objective hypothesis testing and the complex nature of fluid dynamics. In general, the opinions of bloodstain pattern analysts are more subjective than scientific. In addition, many bloodstain pattern analysis cases are prosecution driven or defense driven, with targeted requests that can lead to context bias.

Summary Assessment

Scientific studies support some aspects of bloodstain pattern analysis. One can tell, for example, if the blood spattered quickly or slowly, but some experts extrapolate far beyond what can be supported. Although the trajectories of bullets are linear, the damage that they cause in soft tissue and the complex patterns that fluids make when exiting wounds are highly variable. For such situations, many experiments must be conducted to determine what characteristics of a bloodstain pattern are caused by particular actions during a crime and to inform the interpretation of those causal links and

135

H.L. MacDonell. 1997. Bloodstain Patterns. Corning, NY: Laboratory of Forensic Science; S. James. 1998. Scientific and Legal Applications of Bloodstain Pattern Interpretation. Boca Raton, FL: CRC Press; P. Pizzola, S. Roth, and P. DeForest. 1986. Blood drop dynamics–II. Journal of Forensic Sciences 31(1): 36-49.

136

Ibid.; R.M. Gardner. 2004. Practical Crime Scene Processing and Investigation. Boca Raton, FL: CRC Press; H.C. Lee; T. Palmbach and M.T. Miller. 2005. Henry Lee’s Crime Scene Handbook. Burlington, MA: Elsevier Academic Press, pp. 281-298.

137

W.J. Chisum and B.E. Turvey. 2007. Crime Reconstruction. Burlington, MA: Elsevier Academic Press.

138

See “Bloodstain Pattern Examiner Certification Requirements.” Available at theiai.org/certifications/bloodstain/requirements.php.



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