The Devil I Knew: Unmasking a Serial Killer

The Devil I Knew: Unmasking a Serial Killer

"There's a truth to everything I said, Jon. This is a puzzle. You have to figure it out."

The puzzle included numerous murders across the western United States that serial killer Scott Kimball described in detail as we sat across from each other at a table in the Colorado Penitentiary in 2011. I had no doubt he had killed at least as many people as he claimed-considering how easily he had conned the FBI, and local police and judicial systems across many states while he was killing the four victims we knew about.

The Devil I Knew: Unmasking a Serial Killer is a true crime novel about the fifteen-year investigation by former FBI Special Agent Jonny Grusing into the homicides committed by Scott Kimball. Kimball was an FBI informant in the early 2000s, reporting on multiple murder-for-hire cases while secretly making people disappear. Working closely with the FBI's profiling unit, a local detective, and state and federal prosecutors, Agent Grusing was the primary FBI investigator assigned to determine what had happened to the missing people. This team faced near-impossible tasks to prove homicide cases against Kimball and to locate his hidden victims. The book delves into the principles Agent Grusing learned from the FBI's Behavioral Analysis Unit and how he applied those tactics as he interviewed and interacted with this highly intelligent, manipulative murderer. The story accounts for body recovery trips into the mountains of Colorado and outside of the state, includes extensive conversations with the victims' families, explores other unsolved murders possibly tied to Kimball, and assesses the complete devastation this wolf in sheep's clothing left behind.

Jonny Grusing, a retired FBI Special Agent, spent 23 of his 25 years in the Bureau working on significant violent crime cases in Colorado, many of which are featured on true crime documentaries. Jonny combines much-needed humor with his incredibly harrowing account of tangling with the inhuman manipulation, deceit, and violence of this serial killer. This non-fiction novel will educate readers about the bare-knuckled challenges and the soul-draining experiences of facing off with a dangerous psychopath.

"A riveting inside account of Grusing's exhaustive investigation and face-to-face dealings with the man who simply called himself . . . Hannibal." -Robert Dean, Dateline, NBC

"Get ready for a roller coaster ride deep into the mind of pure evil." -John Quinones, 20/20, ABC

Author: Jonny Grusing
Publisher: Grusing Consulting, LLC
Published: 09/14/2025
Pages: 360
Binding Type: Paperback
Weight: 1.06lbs
Size: 9.00h x 6.00w x 0.80d
ISBN: 9798999564504

About the Author
Grusing, Jonny: - Jonny Grusing was a Special Agent (SA) with the FBI's Denver Division from 1996 to 2021. For 23 years of his career, he worked violent crime matters to include missing persons, serial killers, federal jurisdiction homicides and mass attacks. From 2008 until his retirement, he served as the Behavioral Analysis Unit (BAU) Coordinator for the division. SA Grusing received extensive training from the profiling unit during these years and employed that training in addressing the serious violent crime cases in Colorado. From 2013 through the present, he has taught hundreds of seminars on profiling serial killers and preventing mass attacks using the sound BAU principles. He was the FBI Case Agent assigned to investigate the homicides of serial killer Scott Kimball from 2006 to 2021.