This is the 1st book in the Sheriff Porter Beck series by Bruce Borges who has a couple of standalone to his credit, but this is his first series.  The second book. Shades of Mercy, is due out this summer.  

The Bitter Past
By Bruce Borgos
2024 / 
Read by James Babson, 10h 1m 
Rating: C / historical fiction / 
Mystery-espionage-thriller 
(#1 in Sheriff Porter Beck series)

From the publisher: 
Porter Beck is the sheriff in the high desert of Nevada, north of Las Vegas. Born and raised there, he left to join the Army, where he worked in Intelligence, deep in the shadows in far off places. Now he’s back home, doing the same lawman’s job his father once did, before his father started to develop dementia. All is relatively quiet in this corner of the world, until an old, retired FBI agent is found killed. He was brutally tortured before he was killed and clues at the scene point to a mystery dating back to the early days of the nuclear age. If that wasn’t strange enough, a current FBI agent shows up to help Beck’s investigation.

From me: 
This was a great concept with some interesting characters, but for me it got confusing with so many characters and the plot didn’t quite stay within the realm of reality. For some reason I found it compelling in its own way so I finished even though it was from the library  and no loss if I didn’t.   It was rather fun in places and relaxin to read.  It’s kind of like a thriller spy novel which takes place mostly on the high desert around the borders of Arizona, Nevada, and Utah borders.