Safety manager pleads no contest in 5-year-old's hyperbaric chamber death

Second-degree murder charge dropped in plea agreement

Jeffrey Mosteller, the safety director of the Oxford Center in Troy, Michigan, pleaded no contest Tuesday to involuntary manslaughter in the death of 5-year-old Thomas Cooper, who was killed when an oxygen chamber exploded at the clinic on Jan. 31, 2025.

Michigan Attorney General Dana Nessel said the plea agreement specifies a minimum prison sentence of 19 months for Mosteller. A second-degree murder charge, which carries a potential life sentence, was dropped as part of the deal in Oakland County court.

“A young child lost his life in a completely preventable tragedy because this defendant allowed an outdated device to operate in defiance of safety standards,” Nessel said in a statement.

The hyperbaric chamber exploded at the Oxford Center on Jan. 31, 2025, killing Thomas Cooper and injuring his mother, who was standing nearby. After the explosion, the clinic said it could not explain why it happened.

In February, an Oakland County judge noted that safety concerns raised by employees “appeared to be all but ignored,” according to court records.

Three other individuals charged in connection with the explosion remain awaiting trial. Tamela Peterson, the clinic’s CEO, and Gary Marken, a manager, each face one count of second-degree murder, a potential life offense, or alternatively one count of involuntary manslaughter, a 15-year felony. A fourth defendant, Aleta Moffitt, also faces charges in the case.

Mosteller’s attorney declined to comment on the no-contest plea.