The youth is on parole for a felony weapons violation in another county. His name has not been made public.
TYC was required to inform Anderson about the student's criminal record within 24 hours of transfer.
The Austin American-Statesman reported Thursday that the school did not learn about the situation for a month and only because his records arrived, indicating he was from a detention facility.
A parole supervisor confirmed only that the student had been on probation for carrying a weapon in "places prohibited."