On a January night in 1988, Thomas Sullivan Jr., age 14, stabbed his mother Betty Ann to death in their Jefferson, New Jersey home, set a fire throughout the house, and slashed his own throat in the family's front yard. The crime shocked the community and left prosecutors and observers grappling with fundamental questions about what could drive a teenager to commit such violence.

That morning, a smoke alarm awakened Thomas Sullivan Sr. and his 10-year-old son Brian. They discovered Betty Ann's body before fleeing the burning house. Both survived the fire, but the family was forever fractured by the tragedy.

Police investigating the scene recovered a handwritten note filled with cult-like symbols found at the house. Prosecutors built their case around Tommy's documented obsession with Satanism, arguing that his fascination with occult ideology had escalated to violence. The theory centered on an argument between mother and son over his interests—a dispute that prosecutors contended triggered the fatal attack.

However, the official narrative hasn't gone unchallenged. Some observers and analysts have pointed to the possibility of undiagnosed mental illness or other undisclosed psychological struggles as potential factors in the crime. The competing explanations reflect a broader tension in how we understand juvenile violence: whether ideology alone can drive such acts, or whether deeper psychiatric issues were at play.

The case remained largely confined to local New Jersey records until recently, when it gained renewed attention through a popular podcast series called "The Devil Within," which accumulated over 30 million downloads and 200 episodes exploring the crime and its circumstances.

Now, the story has reached a wider audience through the documentary series "Let the Devil In," which premiered on MGM+ on August 31, 2025, and later became available on Amazon Prime Video for a limited time. The series is executive produced by horror filmmaker Eli Roth, known for his work in the genre. The documentary examines both the facts of the crime and the enduring questions surrounding Tommy's motivations.

The case presents difficult questions for criminologists and true crime observers. Teenage violence linked to subcultural interests—whether Satanism, gaming, or other pursuits—often becomes a flashpoint for public concern and media scrutiny. Yet determining the actual causal role of such interests versus underlying mental health conditions remains complex. Tommy's note with cult symbols and his documented interest in Satanism formed the prosecution's foundation, but without a clear window into his internal mental state or whether he received any psychological evaluation, the full picture remains contested.

The surviving family members have had to live with the aftermath for decades. The case also raises questions about how communities and institutions recognize warning signs in teenagers and what interventions might prevent such tragedies.

"Let the Devil In" joins a growing catalog of true crime documentaries that revisit cases from previous decades through a modern lens, offering contemporary audiences the chance to examine old crimes with fresh perspective and newly available information. For viewers interested in the intersection of adolescent psychology, criminal behavior, and cultural influences, the series presents material worthy of serious consideration.

While the facts of what happened on that January night in 1988 are established, the deeper "why"—the true motivation behind Betty Ann Sullivan's death—remains a subject of interpretation and debate.

**Sources:** https://www.soapcentral.com/shows/let-devil-in-who-thomas-sullivan-jr-happened-him-disturbing-details-true-crime-docuseries-explored https://www.youtube.com/watch?v=eREvPUBUaBE https://podcasts.apple.com/us/podcast/let-the-devil-in-now-on-amazon-prime/id1569216112?i=1000746815891