Summary of Murdock et. al
Introduction
Due to the nature of the criminal justice system, or any system that pins individual’s against one another, there will always be questions raised in regards to the evidence. Critics of firearm and toolmark evidence examination say that there is little to no backing in the field due to the lack of statistical evidence. One researcher says that unless a RMP is given, the value of the evidence is inconclusive.
This argument is based in that an examiner in these fields will testify to an “absolute certainty” instead of a “practical certainty”. This is not the case in most situations. It is also noted that these examiners are not neglecting to find statistical backing for their work. There has been some headway and models are being developed but each has its problems and they cannot do everything.
RMPs have featured in DNA analysis, but the nature of toolmarks and firearms requires a different way of looking at them. It often askes the proportion of mistakes to positive identifications.
Review of the Current Literature in Statistical Applications for Firearms and Toolmarks
To date there have been multiple studies conducted to give a statistical basis to forensic science. It was indicated in 1935 that data would need to be collected and the process started. Papers were published from 1949 to 2012 and gave different perspective models and strategies for applying statistics to forensic science. Many of these studies looked into consecutive matching striations (CMS), known matching (KM), known non-matching (KNM), and likelihood ratios (LRs). A specific landmark study published in 1959 involved bullets and the “estimation of CMS run lengths of various sizes for known matching striation patterns and known non-matching striation patterns”.
Current State of the Use of RMPs in Firearm and Toolmark Identification
Due to the nature of DNA and how it both forms and is read, an RMP can be applied. An all-encompassing model for toolmarks and firearms dose not exist, but despite this it can be assumed that the error rates are low due to the models that are present. In addition, when compared to other error rates in the court system, this rate is much lower. In the end, it is not known if there will be a way to create a RMP for firearms that will satisfy everyone. If it is possible, it will be extremely difficult to create an RMP for this area due to the change and remodeling of the microscopic surfaces of interest over time. Authors are approaching this challenge carefully.
Absolute Versus Practical Identification and Subjectivity
It is often believed, due to misrepresentation in the media and through criticisms that firearm and toolmark examiners testify to an absolute certainty. In reality, this is not the case. “Absolute certainty, opinions may have been used in the past, but are not the case in the present day field. In addition, the subjectivity of bullet examination comes into play after a number of non-subjective measurements that will greatly reduce the number of possible matches. There are many other fields and situations were subjective conclusions are either the basis for further examination or an overall assessment.
Title & Abstract Discussion
A title is meant to both attract potential readers while also giving one an idea as to what they will be reading about. After reading this particular paper, I believe it is safe to say that the title misrepresented the content that was presented. “The Development and Application of Random Match Probabilities to Firearm and Toolmark Identification” is a title that leads one to believe that the paper will contain research on this subject. It sounds like the author(s) will be presenting on how they either have been working towards or have developed some type of statistical model in this field. Upon reading this paper, it does not present any original research and only lists past studies when giving data.
In regards to the abstract, it serves as little more than a teaser for the rest of the paper. It does not offer any solid fact or any of the papers conclusions other than saying that much of the criticisms facing the field are “misinformed and, at worst, punditry”. Based on what we have learned in workshops, from our primary investigators, and from our graduate student mentors, an abstract should be a summary of the paper that lays everything out in 150-200 words. This abstract only informs the reader on their views of the field. They do not offer any initial backing or findings to support this claim.
Lastly, the authors conclude the abstract by saying that they will “point out the logical fallacies in the arguments of a small group of pundits” and “give a balanced view of the literature regarding random match probability models and statistical applications”. While this does lay out their paper, it does not provide any initial support or conclusions. In addition, the paper provides little in regards to the opposing view. They say on multiple occasions that they can’t confirm without a shadow of a doubt, but never provide balance through a study or any hard findings.