Overview
- Jeffrey Mosteller, the Oxford Center safety director, entered a no-contest plea on Tuesday, July 21, 2026, to one count of involuntary manslaughter in the death of 5-year-old Thomas Cooper.
- Under the plea agreement filed in Oakland County court, Mosteller faces a sentencing range of 19 months to 15 years and is scheduled to be sentenced on August 31, 2026.
- Prosecutors say the Jan. 31, 2025, hyperbaric chamber explosion that killed Cooper was caused by a static spark and that staff repeatedly ignored safety protocols such as using grounding wrist straps, avoiding dryer-warm blankets and banning polyester materials.
- Three other Oxford Center employees remain criminally charged: founder and CEO Tamela Peterson and manager Gary Marken face second-degree murder or involuntary manslaughter counts while operator Aleta Moffitt faces involuntary manslaughter and falsifying records, and all have upcoming court dates.
- The Cooper family’s $100 million wrongful-death lawsuit against the clinic, the four employees and the chamber’s manufacturer remains active, and prosecutors’ claims that industry and manufacturer (NFPA and Sechrist) rules were ignored could influence both civil liability and broader scrutiny of hyperbaric practices.