In this episode of Zone 7, CSI Sheryl McCollum welcomes back Dr. Katherine Ramsland and Tracy Ullman to discuss the release of their documentary The Serial Killer’s Apprentice. This two-hour film revisits the chilling case of Elmer Wayne Henley Jr. and Dean Corll, blending archival footage, exclusive interviews, and rare audio recordings.

Dr. Ramsland and Ullman share behind-the-scenes insights on producing the documentary. They reveal what has surfaced since the book’s release, and why this case, rooted in grooming, complicity, and trafficking, continues to offer powerful lessons today.

 

Resources:

• Zone 7 Part I The Serial Killer's Apprentice | The Story of Elmer Wayne Henley Jr.
• Zone 7 Part II How to Prevent Young People From Falling Victim to Predatory Criminals
• The Serial Killer's Apprentice
• How to Catch a Killer
• The Mind of a Murderer: A Glimpse into the Darkest Corners of the Human Psyche, from a Leading Forensic Psychiatrist
• John Wayne Gacy: Devil in Disguise
• The Serial Killer’s Apprentice documentary is now streaming on HBO Max
• (Originally aired on Investigation Discovery (ID) on August 17, 2025)

 

Highlights:

• (0:00) Sheryl kicks off Zone 7 with Dr. Katherine Ramsland and Tracy Ullman, introducing The Serial Killer’s Apprentice documentary
• (2:00) How the documentary expands on the book with new interviews, archival footage, and Henley’s own voice
• (4:00) Condensing the sprawling Dean Corll case into a two-hour film without losing depth
• (8:45) “Corll picked two adolescent boys to do his dirty work for him.” – Dr. Ramsland on how predators groom children into crimes
• (11:00) The purpose of the documentary: helping parents, teachers, and kids recognize signs of grooming and recruitment
• (12:45) The Devil’s Den murders and how predators hide in plain sight
• (17:15) Henley’s cries for help that were ignored, and how the film reframes him as both victim and accomplice
• (22:15) Tracy Ullman urges viewers to move beyond the old “fixed villain” narrative, while Henley confronts the reality of being part of a trafficking network and how it reshaped his view of guilt and remorse
• (32:00) Henley’s evolving understanding of his role, his remorse, and why the full truth behind these crimes may still be unfolding
• (36:45) Sheryl closes with a quote from A Darker Shade of Magic: “Some people steal to stay alive. Some people steal to feel alive.”

 

Thanks for tuning in to Zone 7. If you are enjoying the podcast, please leave a rating and review. Your support helps us continue to educate, investigate, and advocate.

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Sheryl “Mac” McCollum is an Emmy Award-winning CSI, a writer for CrimeOnline, forensic and crime scene expert for Crime Stories with Nancy Grace, and co-author of the textbook Cold Case: Pathways to Justice. She is the founder and director of the Cold Case Investigative Research Institute, a national collaboration that advances techniques for solving cold cases and assists families and law enforcement with unsolved homicides, missing persons, and kidnappings.

Dr. Katherine Ramsland is a professor of forensic psychology at DeSales University and the author of numerous books and articles. Her works include How to Catch a Killer, The Mind of a Murderer, and The Serial Killer’s Apprentice. She is also a frequent contributor to crime documentaries and television shows, where she shares her expertise on serial killers, criminal behavior, and the psychology of predators.

Tracy Ullman is a writer, producer, and investigative journalist who specializes in true crime storytelling and victim advocacy. She co-authored The Serial Killer’s Apprentice with Dr. Katherine Ramsland and has conducted research into John Wayne Gacy and sex trafficking networks. She also served as an executive producer on The Serial Killer’s Apprentice documentary, helping bring new perspective to the story of Elmer Wayne Henley Jr. And Dean Corll.

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