OAKLAND COUNTY, Mich. – Four employees were arraigned on charges in connection to the death of a 5-year-old boy who was killed in a hyperbaric chamber explosion in Oakland County.
Thomas Cooper was killed on Friday, Jan. 31, 2025, when the hyperbaric chamber he was receiving treatment in at the Oxford Center in Troy exploded.
CEO, 3 other Oxford Center workers arraigned
The founder of the Oxford Center and three other employees were arraigned before Magistrate Elizabeth Chiappelli on Tuesday, March 11.
Tamela Peterson, 58, of Brighton, the founder and CEO of the Oxford Center, was arraigned on second-degree murder charges and given a $2 million bond.
Two other workers, Jeffrey Mosteller, 64, of Clinton Township, the safety director, and Gary Marken, 65, of Spring Arbor, the primary management assistant, were also arraigned on second-degree murder charges. Bond was set at $250,000 for these two men.
These three workers have also been charged with alternative counts of involuntary manslaughter, meaning a jury will be able to decide which charge properly fits the defendants' conduct, according to Attorney General Dana Nessel.
A fourth employee, Aleta Moffitt, 60, of Rochester Hills, the operator of the hyperbaric chamber, was arraigned on the charges of involuntary manslaughter and falsifying medical records. Her bond was set at $100,000.
Local 4 has learned that Marken and Moffitt have posted bond and are in the process of being released.
Hyperbaric chamber was ‘ticking time bomb,’ prosecutor alleges
During the arraignments, Assistant Attorney General Chris Kessel accused the center’s primary management assistant, Gary Marken, of being personally involved with altering the hyperbaric chambers to make them seem safer than they were.
“In this case, it was this one specific machine that multiple witnesses have identified that this defendant was working on, rolling back those numbers, in essence, I hesitate to use this phrase, judge, but I don’t know one that’s more applicable. He was literally making this a ticking time bomb. That’s what his actions were doing.”
The prosecutor expressed concerns about his alleged role in tampering with the numbers on the machines when addressing bond.
“This defendant, as part of his bond conditions, should have nothing to do with the Oxford Center or any other hyperbaric oxygen treatment facilities, or treatments or anything of that nature,” Kessel said.
But Marken’s attorney, Raymond Cassar, claimed that Marken hadn’t been at the Oxford Center’s Troy location in three years.
“I don’t know where the information is coming from that he is rolling back any of these things, but I can tell you that we’re confident he hasn’t been to that facility because he worked at the Brighton facility.”
Cassar also said that Marken was a facilities manager and didn’t operate the hyperbaric chambers.
The attorney also expressed his frustrations about Marken being arrested at his home on Monday, March 10.
“I will tell you the most important thing the court should know and take into consideration is that we were offered an opportunity to sit down with the authorities, and we agree to sit down with the authorities, with the understanding that we could bring this man in when the charges came due.”
Cassar said because Marken cooperated with the authorities, they were under the impression that they could bring him in, as opposed to him being brought in with handcuffs. He also stressed Marken’s cooperation as a point for the judge to consider a personal bond.
Judge: ‘I can’t risk that happening to any other human being.'
“In this case, by the very nature of the allegations, a hyperbaric chamber with high saturations of oxygen is essentially a ticking time bomb,” said Chiappelli. “If that unit is tampered with, it becomes Russian roulette for whoever gets into that chamber.”
When setting bond for Marken, Chiappelli said she had to ensure that something like this never happens again.
“I can’t risk that happening to any other human being on the face of the planet Earth,” said Chiappelli. “That is such a torturous, horrific, heinous image. I have to make sure that you never have the ability to come near. I’m not saying never; I’m saying while you’re on my bond, not come near any sort of facility that participates in the treatment using hyperbaric chambers.”
Chiappelli also said, to her understanding, Marken and Peterson worked “hand-in-glove” and shared an office at the Brighton location.
“If he were to be the person that were doing her bidding, turning these things back, obviously, that’s a very dangerous person in my purview,” said Chiappelli.
Bond was set at $250,000 with conditions that are similar to the conditions given to the other defendants, including that he must wear a steel GPS tether, he can’t have any contact with the family of the victim or his codefendants, must forfeit his passport, and he cannot return to either Oxford Center location or participate in hyperbaric chamber treatment at any facility.
Marken is scheduled to appear in court again for a probable cause conference on March 19 and a preliminary examination on March 26.
You can watch the arraignments in the video below. Marken’s arraignment begins at the 23:21 mark in the video.
Previous coverage:
