Police arrested a former Houston day care bus driver Tuesday in connection with the death of a 3-year-old boy who was found dead in a hot bus last year.

Maurice Mitchell, 62, was indicted Friday on a charge of second-degree injury to a child by recklessly causing serious bodily injury or death. The indictment was handed down exactly one year after the death of Raymond “R.J.” Pryer Jr.

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Investigators say Raymond and 28 other children went on a field trip to a local park with the Discovering Me Academy on July 19, 2018. Day care workers did not notice the boy was missing until 6:30 p.m. when Raymond's father arrived to pick him up.

Staffers found Raymond unresponsive inside the bus and he was pronounced dead at a local hospital.

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Harris County deputies told FOX 26 their heat gauges showed temperature inside the bus to be 113 degrees when they first arrived at the scene.

Prosecutors allege Mitchell disengaged a passenger safety alarm, employed to ensure children were not left behind, without checking to make sure anyone was still on the bus.

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“As the summer heat intensifies, we should honor R.J.’s memory by ensuring no more children are left in hot vehicles,” Harris County Assistant District Attorney Michele Oncken said in a statement.

“Remember that the Texas [heat] can be deadly."

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Fox News’ Kira Grant contributed to this report.