The Naturalist by Andrew Mayne

While on a field trip in Montana, Professor Theo Cray hears a horrific story.  A woman has been killed.  He is shocked when he finds out that it was a former student of his, in the area doing field work.  Cray sees the body and although the first impression is that she has been killed by a bear, he doesn't believe it.  He takes pictures and samples and goes to the police with his thoughts only to find that they are determined to put this down to a rampaging animal or alternatively, to charge him as he seems so obsessed with the crime.

He reluctantly leaves the town but he isn't through.  As a computational biologist, he is a scientist and the police's theory just doesn't add up.  He is trained to see patterns where others do not.  In fact, he is just focused enough that he sees things others do not and socially awkward enough that he insists on his theories even when those around him don't believe him.

Theo goes to a neighboring town and tries to work out what happened.  Once he throws out the theory that the death was the result of a bear, he is left with the theory that it is a human killer who is disguising as a bear for the ability to kill without consequences.  Cray works out a theory that shows him the areas that such a killer would tend to target and then searches for missing people.  When he manages to find another body, killed a year before, the police can't ignore him although once again they reach for the comfortable animal killing idea.  Although the police don't believe him, the killer does and can't believe someone has managed to break his decades long streak of killings.  The killer is determined to put an end to Theo's theory and how better to do it than to put an end to Theo?

This is the first in a series of mysteries by Andrew Mayne, who is best known for his work as a magician.  He has both a TV series and a podcast about illusion which makes the sleight of hand necessary in a mystery secondhand to him.  In Theo Cray, he has created a fascinating character whose quirks seem believable and whose name, Cray, is a sly illusion to the Cray supercomputer which he is similar to.  This book is recommended for mystery readers.