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The Devil I Knew: Unmasking a Serial Killer
The Devil I 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 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
“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 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
360 pages, Hardcover
Published August 28, 2025
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87 people want to read
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Displaying 1 - 2 of 2 reviews
December 3, 2025
I was so excited to read this & it did not disappoint. I don’t know Jonny Gursing but have followed many of his cases. When I was 19/20 years old, a young female was found murdered (Cat) behind a small strip mall where I was working at the time. I was young & beautiful. The murder of Cat shook my parents to the core. So much so, I wasn’t allowed to work there anymore and my parents kept me as close as possible. I remember reading about how her hands looked as though they were surgically removed. I wasn’t into trials & investigations until many years later so I never really followed the case at the time.
A couple of years ago I had a dream about the young woman (Cat) they found behind my work. That day I spoke with a work colleague who grew up in the same area. She remembered it vaguely. Later that night I researched it a little to see if they ever caught the person. “F🤬🤬king Scott Kimball” name kept coming up in articles. I knew of Scott and seen some documentaries but really never dug into him until this past year. It wasn’t Scott that caught my interest in his case. It was Agent Gursing’s interrogations and knowledge that caught my interest.
This book was very well written and did an exceptional job of telling some of his victims stories, even uncle Terry’s.
My prayers go out to Bob & all the victims families ♥️.
Side note: I had a dream last night that Scott Kimball & Letecia Stauch were in an interview room & Gursing said “Take your best shot at them & believe nothing”. 😬😬 more like a nightmare.
A couple of years ago I had a dream about the young woman (Cat) they found behind my work. That day I spoke with a work colleague who grew up in the same area. She remembered it vaguely. Later that night I researched it a little to see if they ever caught the person. “F🤬🤬king Scott Kimball” name kept coming up in articles. I knew of Scott and seen some documentaries but really never dug into him until this past year. It wasn’t Scott that caught my interest in his case. It was Agent Gursing’s interrogations and knowledge that caught my interest.
This book was very well written and did an exceptional job of telling some of his victims stories, even uncle Terry’s.
My prayers go out to Bob & all the victims families ♥️.
Side note: I had a dream last night that Scott Kimball & Letecia Stauch were in an interview room & Gursing said “Take your best shot at them & believe nothing”. 😬😬 more like a nightmare.
November 29, 2025
It was extremely interesting to read a book by someone you know. Jonny and his wife attended the church where we go, Jonny even teaching my son’s class for a bit. Though I’ve always known he was an FBI agent, I had no idea this LONG lasting case was something he was working on. I’m not sure I could have condensed it down and made it readable but I’m very glad he did!
Displaying 1 - 2 of 2 reviews