OAKLAND COUNTY, Mich. – The four workers charged after a 5-year-old boy was killed in a hyperbaric chamber explosion at an Oakland County health care center are scheduled to appear in court.
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.
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The CEO and three workers are expected to appear before Oakland County Judge Maureen McGinnis in 52-4 District Court on Tuesday, Dec. 16, for a continuation of their preliminary examination.
This will be the sixth day that the workers appear in court for this key hearing.
The purpose of a preliminary examination is to determine if a felony was committed and if there is probable cause to send a defendant to a higher court, where they could then face trial.
Charges
Peterson, the Oxford Center’s founder and CEO, along with Mosteller, the safety manager, and Marken, the primary management assistant, were charged with second-degree murder.
They were also given the alternative charge of involuntary manslaughter, which means that a jury will decide which charge accurately fits their conduct.
Moffitt, who was allegedly operating the hyperbaric chamber at the time of the explosion, was charged with involuntary manslaughter and falsifying medical records.
Allegations
The four workers are accused of ignoring several safety guidelines for operating hyperbaric chambers, including not using 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.
Testimony so far
During the hearing, the first witness called to testify was Tiffany Hosey, a Certified Hyperbaric Technologist (CHT) and Certified Hyperbaric and Wound Specialist (CHWS), who worked at the Oxford Center from fall 2020 until spring 2024.
She said she was let go after she expressed safety concerns, including patients in hyperbaric chambers being grounded. She said she questioned Mosteller regarding policies over the phone, through email, through Teams messages and in person.
Hosey said she asked Peterson multiple times why grounding straps weren’t used. She reportedly said grounding straps presented suffocation risks and that Mosteller had done independent tests that “proved” they weren’t necessary.
The test reportedly had a staff member lying still on a stretcher without a sheet, not in a pressurized hyperbaric chamber. The test did not alleviate Hosey’s concerns.
Francois Burman and Andrew Melnyczenko, experts who each have nearly 30 years of experience working with hyperbaric chambers, also testified about the importance of grounding wrist straps in monoplace chambers.
He said that while a grounding strap doesn’t eliminate the risk of discharge, it reduces it to being nearly impossible. He added that he would never allow a child in a monoplace chamber without a grounding strap.
“The risk is just too high,” Burman said. “There’s no logical reason to do that.”
Andrew Melnyczenko also highlighted that safety protocols, including documented safety pauses and grounding checks, were not consistently followed at the Oxford Center.
Troy Detective Ryan Whiteside testified about reviewing video footage of Thomas’ 35 treatments, noting the child never wore a grounding bracelet and was often given blankets right from the dryer, which contributes to static buildup.
The lead detective on the chase, Troy Detective Danielle Trigger, described arriving at the “chaotic” scene at the Oxford Center on the day of the explosion. She testified that grounding wrist straps were found unused in a “junk drawer” at the facility, indicating they were not routinely used.
Trigger also reviewed training materials, which emphasized the importance of grounding patients and fire prevention protocols, and shared details about phone calls that ended a police interview with a defendant.
Troy Fire Department Deputy Chief Shawn Hugg testified about securing the Oxford Center after the explosion and his investigation into the cause of the fire.
Hugg said static electric discharge was the likely cause of the fire, meeting all five conditions necessary for a static-induced fire ignition, but also testified that there is still some evidence that needs to be tested.
Defense attorneys are expected to continue cross-examining Hugg in the afternoon on Tuesday, Dec. 16, 2025, when the hearing resumes.
For a full deep dive into what we learned during previous days of the preliminary hearing, check out the following stories: