Introduction
Bloodstain pattern analysis was used as a method of preliminary assessment of a crime scene long before the scientific approach has entered the field of forensics. Police and criminal investigators identified potential victims by the presence of bloodstains or drops on their clothing or bodies. Since then the process of visual analysis has sophisticated manifold and evolved into a separate field of practical study within forensic science. Recently, there has been a certain controversy among researchers and bloodstain analysis about the validity, reliability, and legal value of this method, which testifies to the relevance of examining blood spatter analysis in its application to a real-world case with implications drawn for modern forensics.
Case Description
The relatively modern case in which blood spatter analysis was of the essence to the prosecution was one of David Camm. At 9.30 p.m., Camm telephoned Sellersburg, Indiana State Police station and claimed that three members of his family, including his wife, Kimberly, son Brad, and daughter Jill were shot to death in the garage of their family house. As per the later commentary of Camm, he returned home after finishing his basketball match (where he spend the time from 7 p.m. till 9.20 p.m.) near the local church and found his wife dead on the floor of the garage (National Registry of Exonerations, 2013). He found his children inside the car in the backseat.
As he added, he thought that his son Brad might still be alive, so he extracted him from the car and performed cardiopulmonary resuscitation on him with no result. At this point, he called the police. The police officers found Camm on the floor beside the victims. The daughter and mother were shot to the head, while the son was shot to the chest (National Registry of Exonerations, 2013).
He was charged with the murder of three people and sentenced to a prison term of 195 years. The main evidence against him was the result of the blood spatter analysis performed on his shirt. Camm served 13 years being in the middle of legal action until his release and a drop of all charges in 2013 after a successful appeal to court (Davis, 2013).
Bloodstain Pattern Analysis in the Case
Unlike other similar cases, in this one, both prosecution and defense relied heavily on the evidence of bloodstain pattern analysis. During the investigation, criminal experts managed to find approximately 8 drops of blood on David Camm’s shirt. Prosecution bloodstain pattern analysts, Tom Bevel and Rod Englert claimed that these drops were high velocity spatter (David R. Camm v. the State of Indiana, 2009). They could only have gotten on the shirt as a result of a shot fired at close range or being in direct proximity to the victim at the time when the shot was fired. The defense, however, argued with such interpretation of the findings. Paul Kish, Stuart H. James, and others stated that the pattern might instead signify the fact that Camm’s shirt might have become stained with blood in that particular manner as a result of it brushing against Jill’s hair (David R. Camm v. the State of Indiana, 2009).
The role of bloodstain analysis, in this case, was to determine if the defendant was guilty of murder. By attempting to reconstruct the tragic events, different analysts used empirical evidence and deductive logic to determine if Camm was indeed a killer of his own family. Since no other evidence such as DNA was could not be traced to Camm, and his alibi was rather sound, eight drops of blood found on the shirt of the main suspect was the final straw for the prosecution. According to the blood spatter analysts, this evidence places Camm at the crime scene at the event of the murder and not after, as he and his witnesses claim. Yet, due to the conflicting nature of bloodstain pattern interpretation, the method also served as the basis for defense strategy.
The final decision of the jury was to believe the defendant’s group of researchers as their combined authority outweighed the prosecution’s. In addition, the amount of evidence (only eight spots) was found to be far from convincing. At the time, little empirical evidence existed to conclusively prove either point of view. This limits the results because they have little scientific basis as demonstrated by the case.
The spatter velocity can be defined from the angle from which the droplet struck the surface. The length and width of the resulting stain help determine the speed at which the drop was traveling before it hit the object of analysis. Yet there is still doubt as to how to interpret the stains even though rather exact calculations can be produced. The results of the analysis conducted by Keenan (2012) state that there is significant evidence as to the unique nature of the bloodstain pattern on different fabric types. The research identifies that almost all results of spatter comparisons among different fabrics were dissimilar. She argues that the fact that Jury in Camm’s case found the results inconclusive based on only eight patterns could have been avoided should the evidence she uncovered have been publicized sooner (Keenan, 2012).
Therefore, the science behind the method continues to evolve, yet numerous factors cannot possibly be included in calculations. As such, the fact that one could accidentally replicate the high-velocity pattern by brushing the shirt against blood-stained hair. Application of velocity calculation as the main evidence of the case might have been biased for several reasons. A certain degree of complication might arise from the chemical composition of blood. Not all blood is the same among people, and the presence of illnesses in a person that affects blood composition may also affect the reliability and generalizability of evidence emerging from bloodstain pattern analysis. Physics can also undermine the accuracy of the results. For instance, according to Forensic Security Metrology (n.d.), calculating air and impact material friction can become rather complicated, and lead to errors. In addition, measurement of the origin of blood spatter needs accurate calculation of straight movement and gravitation force.
Importance and Implications of Bloodstain Pattern Analysis
The reason why blood spatters analysis might be of effect and why in certain cases it emerges as primary evidence is the conflicting nature of other types of evidence. As such, the results of DNA tests may be uninformative. Yet as it was pointed out by several public speakers and experts, in blood spatter analysis there is also room for conflict. When such conflict of opinion arises, it automatically states the lack of reliability as a 50 percent chance of error emerges. As the methods of analysis and formulas used by different research groups rarely can be rendered ineffective or biased by other groups, the interpretation of evidence remains in the domain of authority. Provided a majority of experts tend to interpret the pattern in a similar way the decision of the jury can be swayed in the necessary direction as it occurred in Camm’s case. The defense’s cumulative authority and the number of researchers were sufficient for the court to rule in their favor. Such ambiguity that stems from the lack of established procedures and complications of modeling real-life situations speaks to the fact of the scarce reliability of bloodstain pattern analysis. According to Keenan (2012), further research is needed in this area to make this forensic analysis method reliable.
In addition, there is a problem of confirmation bias. Due to the fact that there is more than one interpretation of the pattern, an analyst’s adherence to a certain body of previous evidence, personal experience, or scientific theory could influence the decision-making process. As a result, such an analyst may become unintentionally tempted to give credit to the information that aligns with his or her perception negating contradicting facts.
Conclusion
All things considered, bloodstain pattern analysis does not seem to be a convincing argument in court. Even more so, as evidenced by the David Camm case, the conflict of opinions that stems from the lack of sound and standardized interpretation strategies can undermine the role of the method as a source of convincing and incriminating evidence. In addition, it can only partly place the blame on a certain person as the presence of blood on him or her does not necessarily make them killers. Such a practice as measuring the velocity of the spatter does not stand as evidence in court as it can be replicated with absolutely different implications. Yet, with the emergence of new research, experiments, and patterns, the method can become a sound forensic tool as a part of bloodstain analysis.
References
Brodbeck, S. (2012). Introduction to bloodstain pattern analysis. Journal for Police Science and Practice, 2, 51–57.
David R. Camm v. the State of Indiana, 812 N.E.2d 1127 (2009).
Davis, L. (2013). Ex-trooper was acquitted in family’s death after 13 years in prison. ABC News. Web.
Forensic Security Metrology. (n.d.). Blood spatter analysis. Web.
Keenan, H. K. (2012). A comparison of bloodstains on fabric: Characteristics of impact spatter. Web.
National Registry of Exonerations. (2013). David Camm. Web.