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Collecting Toolmark Impressions For the latest NIJ grant, we need to collect a set of tool marks from screwdrivers held at one of 5 specific angles. To do this, I modeled a jig in a program called openSCAD, which is an open-souce 3d modeling program. Here is the jig in action: Here is a closeup: It does a nice job of creating constant pressure on heavy-duty aluminum foil: Here is one closeup, taken with a Sony a7r3 with a macro lens and two exension rings:

Fitting Signal Detection Theory Models At 2019 IAI in Reno, I presented a talk in which I described how models based on Signal Detection Theory could be used to help summarize the data from proficiency/error rate tests (where ground truth is known). The slides for that talk are found here: IAI 2019 talk on SDT As part of that talk, I created a spreadsheet that allows anyone to explore and fit Signal Detection Theory models.

New Blog! This current blog is hard to maintain, so I’ve started a new blog at the link below: https://blogs.iu.edu/buseylab/

Is the Gaussian (i.e. normal) distribution tenable? We recently documented likelihood ratios for individual print pairs in black box studies: Busey T, & Coon, M. Not all Identification Conclusions are Equal: Quantifying the Strength of Fingerprint Decisions. In press, Forensic Science International. pdf. Also see link to Presentation This paper is important because it demonstrates that for many casework-quality pairs (ones that a majority of examiners with make an identification on) can have strengths of evidence that do not support a phrase such as “Identification”.

Tom’s Brain Surgery In Mid-November 2019 I started waking up at 2am every morning with headaches. This happened to coincide with the time of year where Bloomington gets really dry in the winter, and so I assumed that these were sinus headaches. These got worse, and I started to have balance problems that I assumed were residual effects of the headaches. It took me until the end of January to actually get an ENT appointment.

Toolmark Impression Comparison Interface For the latest NIJ grant, we need an interface that will allow examiners to compare toolmarks from screwdrivers and chisels. We’re in the process of creating software that will allow us to do a virtual splitscreen. The examiner will move the questioned impression around on the screen, and can compare it to one of 5 different exemplar impressions taken at different angles. Here is a mockup of the interface, although the final version will differ: