This is the third book in the Lucena’s Fire series.

Ed Davies is a special kind of criminal investigator. He devised a methodology that allows compilation of data from all the police jurisdictions in a particular area and then sift and sort it to see if patterns develop that overlap boundaries. When a jurisdiction believes they have a single person or group committing crimes and don’t have the resources to follow every lead, they call Ed. He is not confined to the official methods of investigation and has a history of success.

You can buy Linker here