The best part of a book event almost never happens on the main stage. It happens in the hallway afterward, chatting with other attendees as we trade war stories.
This past February, at the Creepy Book Festival, I spent a good while talking with Troy A. Hillman, a retired detective and former CPA who has written a true crime book about a forensic genealogy cold case that sat unsolved in Phoenix for more than twenty years. The book is Chasing Down the Zombie Hunter (Pegasus Crime, 2025), and it has been rattling around in my head ever since I finally got down to reading it last month.
The case is a hard one. Two young women, Angela Brosso and Melanie Bernas, were murdered along the Phoenix canals in the early 1990s, and then the trail went cold for two decades. I will not walk you through the worst of what is in those pages. What I want to talk about is the principle the case crystallized for me, a phrase I have adopted as my own working rule for writing killers: pathology trumps intellect.
What I learned is summarized like this: A killer can be careful, organized, even genuinely clever, and still be exposed by the one thing his intelligence cannot govern, which is his own internal behavior that creates a pattern he cannot stop repeating because it’s so engrained in who he is and how he thinks and acts.
The investigators in Zombie Hunter case kept working a stubborn old file until the predator’s own weaknesses finally gave him away.
The concept of pathology trumps intellect is introduced in Hillman’s book as one of the key aspects that helped him and his team solve the crime. It was originally presented to him by a member of the Vidocq Society.
The Vidocq Society
If you write crime and you have never heard of the Vidocq Society, add it to your research shelf today. Founded in Philadelphia in 1990 by William Fleisher, forensic sculptor Frank Bender, and forensic psychologist Richard Walter, it is a members-only group of forensic experts, investigators, prosecutors, and scientists who apply their combined expertise to unsolved cases brought to them by law enforcement and families.
They named themselves after Eugène François Vidocq, the eighteenth-century criminal who was hired by police to help catch other criminals. He was one of the first modern detectives.
The Vidocq crew work away from the cameras, and their cross-disciplinary reach takes on a holistic manner of crime solving. They believe a difficult (if not nearly impossible) case is rarely cracked by one brilliant individual. It takes a roomful of specialists, each holding a corner of the truth.
In this investigation, detectives turned to the Vidocq Society for help building a profile of the unknown killer, and the profile pointed somewhere very uncomfortable… that turned out to be exactly right.
They suggested that the offender was likely a local Phoenix man (not a transient killer) who liked to act out his fantasies, and was already sitting somewhere in the existing case files.
Hold onto that, because it is the heart of how this case was solved.
However, there was a second key tool that Hillman employed to solve this cold case. And it was in its infancy when Hillman used it.
How Forensic Genealogy Cracked It
I have been researching forensic genealogy for a good number of years, long before it became a headline. It runs straight through the last few books I’ve written. It appears in What Darkness Does and again in my forthcoming Walking on White, so this case sits close to my own preoccupations.
Forensic genealogy takes an unknown DNA profile from a crime scene, runs it against public genealogy databases, and builds family trees outward until investigators can narrow a vast field down to a workable few. The pioneer of the technique is forensic genealogist Colleen Fitzpatrick of Identifinders International, whose work in this case predated the famous Golden State Killer identification.
When her team analyzed the zombie killer crime scene DNA, it produced a single, electrifying lead: the surname Miller. (If you want the science underneath all of this, I broke down the fundamentals in DNA Basics 101.)
That is the quiet power of the method. One surname pulled a workable suspect out of a sprawling list. Investigators cross-referenced the name against three Millers they had already connected to the case and arrived at their suspect, Bryan Patrick Miller, a man who carried a juvenile record for stabbing a young woman, Celeste Bentley, who survived.
Bryan Miller had been hiding in plain sight for years as a costumed local character known around Phoenix as the Zombie Hunter. He was a local, who had been interviewed about the case and was already in the files.
I will leave the exact mechanics of the confirmation to Hillman, because the “how dunnit” is the best reason to read his book.
What This Means for Writers
For those of you building killers on the page, this is the lesson I take from it.
We love the criminal mastermind, the cool intellect who plans everything and feels nothing. He is fun to write. He is also, in my experience, the least believable monster on the shelf. The killers who actually get caught are undone by themselves, by the compulsion their cleverness cannot override.
So build the wound first. Decide what drives your antagonist, then his behavior, his mistakes, his weaknesses become the thing that eventually exposes him.
Let him stay close to the investigation and the investigators, because predators like this often believe they are the smartest person in the room. And remember that, more often than not, he is already inside your story long before your detective suspects him.
If you want a structured way to interrogate your own villain, the investigative questions in my Crime Writer’s Toolkit are built for exactly this kind of character work, and cold case construction is the spine of my own Hole in the Woods.
Bryan Patrick Miller went to trial in 2022 and was sentenced to death in 2023 for the two murders he was tried for. Behind every elegant forensic breakthrough is a family that waited decades for an answer, and that is the part I try never to let my fiction forget.
If you are a true crime reader, get Hillman’s book. It is well written, unflinching, and a clear-eyed account of how patient, unglamorous police work and cutting-edge science finally meet.
Troy, thank you for the conversation in that hallway and for your openness and willingness to continue this conversation since then! Keep up the good fight!
