  For several decades, legal and scientific scholars have argued that
conclusions from forensic examinations should be supported by statistical data
and reported within a probabilistic framework. Multiple models have been
proposed to quantify the probative value of forensic evidence. Unfortunately,
several of these models rely on ad-hoc strategies that are not scientifically
sound. The opacity of the technical jargon that is used to present these models
and their results and the complexity of the techniques involved make it very
difficult for the untrained user to separate the wheat from the chaff. This
series of paper is intended to help forensic scientists and lawyers recognise
issues in tools proposed to interpret the results of forensic examinations.
This paper focuses on the tool proposed by the Latent Print Branch of the U.S.
Defense Forensic Science Center (DFSC) and called FRStat. In this paper, I
explore the compatibility of the results outputted by FRStat with the language
used by the DFCS to report the conclusions of their fingerprint examinations,
as well as the appropriateness of the statistical modelling underpinning the
tool and the validation of its performance.
