By Jalen Smith and Louise Henderson

When forensic scientists (people who solve crimes using science) find bones that have been cut with a saw, they try to figure out what kind of saw was used. This can help them narrow down the tools and possibly catch the person who did it.

To do this, they look at the marks left on the bones with the saw. One important mark is called the kerf floor shape, which is the shape of the bottom of the cut made by the saw. Think of it like the footprint of the saw blade.

In the past, scientists would look at these shapes and make educated guesses about the saw based on what they saw with their eyes. But this method wasn’t very precise.

The researcher in this case used some fancy math tools to get a more accurate picture:

• Elliptical Fourier analysis: This is a way to describe complicated shapes using math. Imagine breaking down a shape into simpler parts, like using building blocks to make a model.
• Principal component analysis: This is a method to simplify lots of data by focusing on the most important parts. It’s like summarizing a long story into a few key points.

By using these methods, the researcher could measure the kerf floor shapes more precisely and figure out how well these shapes matched distinct types of saws. This makes their findings more dependable and useful in solving crimes.

Alexis (Lex) VanBaarle, a third-year PhD student’s recently awarded paper presented at the American Academy of Forensic Science examines these characteristics to help forensic scientists.

“Previously all of this kind of analysis did not have the statistical background needed to accurately analyze the shapes and features of the specific saws,” VanBaarle explained. “What this paper does is it allows us to have more data available when testifying on these specific crimes and tell a more complete story of the bones examined, our science can be wrong, and it is not always going to be 100% and we have limitations. And so, finding those limitations and defining that limitation I think is super important” she added.

VanBaarle’s other research interests includes Forensic Anthropology, Skeletal Biology, Skeletal Trauma Biomechanics and Skeletal History. All of which informs her work in shape analysis.

“I think trauma is interesting because there’s so many different things that can impact it. Two different individuals can have the same kind of thing happen to them. Analyzing these fracture patterns or different things like that can help to provide justice for these victims,” VanBaarle concluded.