The four people charged in the death of 5-year-old Thomas Cooper, who died in a hyperbaric chamber explosion in January at The Oxford Center, were back in court on Monday for the continuation of their preliminary examinations.

CEO Tamela Peterson, safety director Jeff Mosteller and primary management assistant Gary Marken were charged with second-degree murder. Additionally, Aleta Moffitt, who was the operator of the hyperbaric chamber, was charged with one count of involuntary manslaughter and one count of intentionally placing false information on a medical record as a medical provider. 

The first witness to take the stand on Monday was Andrew Melnyczenko, who serves as the safety director for hyperbaric chambers at the Mayo Clinic. He testified that The Oxford Center was not operating up to industry standards by failing to use grounding straps.

He also testified that straps are critical from a safety perspective by preventing the buildup of static electricity that could otherwise lead to a spark inside the chamber.

When asked by an attorney if it appeared that Thomas was wearing a grounding strap at the time the fire started, Melnyczenko said, "It did not."

"Because the patient was not grounded continuously with skin contact on the wrist strap, if he had built up static and then come in contact with a grounded surface, that increases the potential for a static discharge to occur," Melnyczenko said.

Majid Mashayekh, safety director at Sechrist Industries, which makes those hyperbaric chambers, testified that failure to use grounding straps would be neglecting a major requirement written in the operations manual. 

"It is required to make sure the patient is grounded, and in order for the patient to be grounded, you must have the wrist strap. It does eliminate the risk of static electricity," Mashayekh testified.

There was also some discussion in court that the chamber had reached its product life expectancy by the time the child was in it. However, there's still some confusion as to whether a technician who serviced the chamber made a mistake, or if the chamber in question was sold before the incident happened. 

The preliminary exam hearing continues on Tuesday.