One of the four people charged after a 5-year-old boy was killed in a hyperbaric chamber explosion at an Oakland County health care facility in January 2025 has pleaded no contest.
Tamela Peterson, 59, of Brighton, Jeffrey Mosteller, 65, of Clinton Township, Gary Marken, 66, of Spring Arbor, and Aleta Moffitt, 61, of Rochester Hills, were charged after Thomas Cooper was killed when the hyperbaric chamber he was receiving treatment in exploded at the Oxford Center in Troy on Jan. 31, 2025. The boy’s mother was also injured in the explosion.
Thomas Cooper, 5, was killed in a hyperbaric chamber explosion on Jan. 31, 2025. (Cooper Family)
Mosteller, the safety manager, along with Peterson, the Oxford Center’s founder and CEO, and Marken, the primary management assistant, were charged with second-degree murder and involuntary manslaughter.
Moffitt, who was allegedly operating the hyperbaric chamber at the time of the explosion, was charged with involuntary manslaughter and falsifying medical records.
The four workers are accused of ignoring several safety guidelines for operating hyperbaric chambers, including failing to use a grounding wrist strap, rolling back the chamber cycle count, giving the 5-year-old boy a blanket straight from a running dryer, using polyester pillows and more.
Tamela Peterson, Jeffrey Mosteller, Gary Marken and Aleta Moffitt (left to right, top to bottom) in court on Tuesday, Feb. 10, 2026. (WDIV)
On July 21, Mosteller pleaded no contest to involuntary manslaughter. The second-degree murder charge was dismissed. He is scheduled to be sentenced on Aug. 31 at 8:30 a.m.
Read previous coverage on the case here.
Peterson is scheduled to appear in court on July 22 for a motion hearing, and Marken and Moffit are scheduled to appear in court on July 27 for a pretrial hearing.
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