Deborah Denise St. Charles, 51, is pictured in this handout photo obtained by Reuters August 10, 2017. Orlando Police Department/Handout via REUTERS

(Reuters) - A 51-year-old female driver for an Orlando daycare center was arrested on Thursday for aggravated manslaughter in the death of a 3-year-old boy who was left for hours inside a van belonging to the center on a hot Florida day, police said.

Police named Deborah Denise St. Charles of Orlando as the driver of the vehicle in which the child, Myles Hill, was left for most of the daylight hours on Monday.

The local medical examiner who performed an autopsy on Hill ruled the toddler died as a result of “hyperthermia due to environmental exposure,” according to an arrest affidavit.

St. Charles also worked in a classroom at one of the two Orlando daycare centers owned by Little Miracles Academy, and was in one of the classrooms while Myles was left outside in the center’s parking lot in the van, the affidavit said.

The affidavit said St. Charles did not follow Florida Administrative Code for child care facilities, including reporting in a driver’s log that each child, by name, has left the vehicle. Also, the affidavit says, she did not make the required visual sweep of the vehicle to ensure that no child was left inside, nor did she get a signature of a second child car facility staff member verifying that the driver’s log shows that each child has left the vehicle.

Orlando police on Wednesday conducted a simulation of the conditions they believe the boy suffered before death, the affidavit said.

During the simulation, at about 10 a.m. ET, when Myles had been in the vehicle for just an hour, the interior temperature was already 115 degrees Fahrenheit (46 Celsius), the affidavit said.

By noon it had reached 133 degrees F (56 C), and by 3 p.m. it was 144 degrees F (62 C), according to the affidavit.

On Wednesday, the owner of the Little Miracles Academy, Audrey Thornton, said the person who drove the van had been fired. Also on Wednesday, the state regulator of daycare centers ordered Little Miracles’ two daycare centers in Orlando to close until the regulator deems them safe.