Police say administrators found out about the crime by accident, after reviewing surveillance video from the bus on another matter.
Buses rolled out through the Wappingers Central School District Wednesday, but there was one vehicle not in service, a bus that sits in a parking at state police barracks as evidence in a criminal investigation.
It was on board that police say 57-year-old Charles Kane, a bus monitor, sexually assaulted a special needs student.
The victim, a severely disabled teenage girl, attends a facility out of the county but lives in the district and was being transported back home for Thanksgiving.
District officials happened to be reviewing surveillance camera footage for an unrelated matter when they came across the inappropriate activity.
State police and parents were immediately notified.
Kane has worked for the school district for 10 years.
An investigation is underway to see if there are any other victims.
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