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The importance of bloodstain patten research and experimentation cannot be overstated. Without a sound scientific foundation, investigators may have difficulty correctly interpreting bloodstain patterns and using that information to identify the sequence of events at a crime scene. Scientific research results can help improve our understanding of bloodstain behavior, leading to more accurate interpretations of bloodstain patterns.
The scientific method is the foundation of all scientific research, and investigators must use this process. The scientific methodology involves the collection of data, the analysis of that data, and the formulation of hypotheses based on that data. Scientific research results can test these hypotheses and improve our understanding of bloodstain behavior. Using the scientific method allows investigators to approach bloodstain pattern analysis with a rigorous and systematic approach, which is essential for accurately interpreting bloodstain patterns.
Investigators should know that not all bloodstain pattern research and experimentation is conducted in a laboratory setting. Field research can also be valuable in understanding bloodstain behavior. Field research involves studying bloodstains at real crime scenes and can provide essential information about how blood behaves in actual situations. This information can improve our understanding of bloodstain behavior in a laboratory setting.
It is important to note that scientific research and experimentation are ongoing, and discoveries are constantly being made that can improve our understanding of bloodstain behavior. Therefore, investigators must keep up-to-date on the latest research to ensure they use the most current information when analyzing bloodstain patterns.
Authored by John Calvin Gaziano – MFS, MS, CBPA, CSCSA
The purpose of the study was to determine the error rates in area of origin analyses among law enforcement personnel and to ascertain whether the reconstructions were within acceptable limits. Sixty-eight novices in bloodstain pattern analysis (BPA) from multiple law enforcement agencies in Northern California participated in the study. Subjects used two different methods of measuring photographs of bloodstains with known impact (alpha) angles. The subjects also measured the same stains’ directional compass (gamma) angles. Five real bloodstain impact patterns were created and reconstructed by a BPA expert to introduce the variables of gravity and air resistance. An algebraic computer program was coded to create 20,000 synthetic impact patterns from each measurement method for a total of 40,000 random patterns. Each synthetic pattern randomized the subjects’ alpha and gamma measurement data before merging them with the expert’s data to show the deviation in the reconstructed area of origin from the known origin; the X value was 30 cm from a vertical target surface. The study’s results showed that the mean reconstructed difference from the known origin for both measurement methods was slightly smaller than the volume of a racquetball (5.7 cm) and pool ball (5.7 cm to 6.3 cm). This small deviation in the reconstructed origin from the known origin has investigative value in determining the location of a bleeding victim and their posture (standing, kneeling, or lying on the ground) while receiving blows.
Keywords: Area of origin, impact pattern, bloodstain, error rates