FORT LAUDERDALE, Fla. - An investigation of a Florida school shooting that left 17 dead last year is expanding to include the school's principal.

Broward County Public Schools announced Thursday that Marjory Stoneman Douglas High School Principal Ty Thompson will remain at the school, though his responsibilities are being reassigned. It's unclear why Thompson is under investigation.

District administrators say they are keeping Thompson because of the stability he's provided to the community since the February 2018 shooting.

Three assistant principals and a security specialist were reassigned and removed from the school last fall. The decision followed a meeting of the state commission that investigated the shooting. No official reason was given for the transfers.

School officials hope to have their investigation finished by the end of the school year.

A message seeking comment from Thompson wasn't immediately returned.