TROY, Mich. (WXYZ) — Four employees of the Troy Oxford Center face murder charges in connection with the death of 5-year-old Thomas Cooper, who was killed in a hyperbaric chamber explosion earlier this year.

Watch Carli Petrus's video report: Preliminary hearing continues in hyperbaric chamber death

Prosecutors continued building their case Tuesday, portraying what they say was a serious lack of safety standards at the Troy Oxford Center.

The four Oxford Center team members facing charges are CEO Tamela Peterson, manager Gary Marken, operator Aleta Moffitt, and safety director Jeffrey Mosteller. All face second-degree murder and involuntary manslaughter charges in Cooper's death.

Previous report: Tense day in court during hearing in hyperbaric chamber explosion hearing Tense day in

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