OAKLAND COUNTY, Mich. – The four workers charged in the death of a 5-year-old boy who was killed in a hyperbaric chamber explosion at a health care facility in Oakland County are scheduled to appear in court on Monday.
Tamela Peterson, 58, of Brighton, Jeffrey Mosteller, 65, of Clinton Township, Gary Marken, 66, of Spring Arbor and Aleta Moffitt, 60, 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.
The four workers are set to appear in 52-4 District Court on Sept. 15, 2025, for their preliminary examinations. 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 trial.
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.
Previous court hearings
The four workers last appeared in court together on May 28, 2025, for probable cause hearings.
Since that hearing, Peterson has appeared in court a few times for motion hearings.
In one instance, a judge denied Peterson’s request for an evidentiary hearing to determine the extent of law enforcement’s access and review of privileged materials during the investigation, but granted a request that allowed Peterson to return to the Oxford Center location in Brighton.
However, the judge later decided to reissue the stricter bond conditions after Peterson was accused of violating her bond condition that prohibits her from possessing weapons.
The judge said Peterson had to follow her original bond conditions, which include having no contact with the family of the victim or her codefendants, not returning to either Oxford Center location, not participating in hyperbaric chamber treatment at any facility, wearing a GPS tether, surrendering her passport, not possessing any weapons and only leaving the house for medical appointments, court hearings and meetings with her attorney.
Peterson’s attorney, Gerald Gleeson, said he was prepared to contest the allegations, entered a not guilty plea and requested a hearing.
A date for the hearing was not previously set, but the judge said it would happen right before or after the preliminary examination that is scheduled to begin on Sept. 15.
Bond
Peterson’s bond was set at $2 million, and Marken and Mosteller were initially issued $250,000 bonds, but Mosteller’s bond was later lowered to $50,000.
Moffitt’s bond was set at $100,000.
The three other workers posted their bonds before Peterson, who had asked for her bond to be reduced. The judge denied that request, but Peterson eventually posted the $2 million bond and was released.
Allegations
The workers are accused of ignoring safety protocols for operating hyperbaric chambers, including not using a grounding wrist strap, giving the 5-year-old boy a blanket straight from a running dryer, using polyester pillows and more.
They are also accused of rolling the chamber cycle count back and creating a “ticking time bomb.”