Prosecutors said a safety manager at the Oxford Center conducted “his own experiments” on a hyperbaric chamber to prove to employees it was safe prior to a deadly explosion that killed a 5-year-old boy.

Tamela Peterson, 58, of Brighton, is one of three employees charged with second-degree murder with an alternate charge of manslaughter, to be determined by the jury.

Thomas Cooper was pronounced dead at the scene on Jan. 31 at the Oxford Center in Troy. His mother suffered burn wounds as she tried to save her boy.