Prince George’s County Police said it happened at the Rieg School in Bowie on September 1.
A health aid assaulted a 20-year-old special needs student on board a parked bus, police said.
Now, authorities are reviewing surveillance video that was handed over to police on Sept. 14.
Parents want to know if a delay was intentional.
“Sadness, anger,” one parent said. “Happiness because now somebody will be forced to open up the can of worms to find out what may be happening to numerous kids.”
Police said the alleged abuser was not a direct school employee.
Five other school employees have been placed on leave.