Michigan judge orders 4 people to stand trial in fatal hyperbaric chamber explosion

A judge on Tuesday ordered four people to stand trial more than a year after a hyperbaric chamber explosion in Troy, Michigan, killed a 5-year-old boy.

Former Oxford Center CEO Tami Peterson, 58, of Brighton, as well as Jeff Mosteller, 64, of Clinton Township, the center's safety director, and Gary Marken, 65, of Spring Arbor, were charged with second-degree murder in the death of Thomas Cooper. A fourth person, Aleta Moffitt, 60, of Rochester Hills, is charged with involuntary manslaughter and intentionally placing false information on a medical record as a medical provider.

No pretrial date has been set. All four people will remain out on bond in the meantime.

During closing statements last month, prosecutors argued that the four people disregarded safety precautions, with former employees testifying that the facility failed to use ground straps. However, the defense argued that their clients believed their operations were safe and would not have put the child in the chamber if they thought otherwise.

Police and firefighters responded to the center on Jan. 31, 2025, and found the child dead in the chamber. The boy's mother, who was near the chamber at the time of the explosion, was injured. It was unclear at the time what the child was being treated for. The Oxford Center provided therapy for kids with various health conditions, including autoimmune diseases, ADHD and autism. 

The Michigan Attorney General's Office charged all four people two months after the explosion. 

"When professionals entrusted with the care of our children abandon the standards meant to keep them safe, they must be held accountable," said Attorney General Dana Nessel in a statement. "I am relieved that this case will proceed to trial, where we will continue to pursue justice for Thomas and his family."

In January 2026, Peterson was also charged with health care fraud. State prosecutors allege that Peterson had knowledge of and was the direct beneficiary of fraudulent health care claims. An investigation into the alleged fraud began in September 2022, more than two years before the explosion.