Pennsylvania ? A middle school principal accused of selling crystal methamphetamine from his office after school and on weekends was arrested after police found the drug on his desk, authorities said Wednesday.

There was no indication that John Acerra sold the drug to students at Nitschmann Middle School, where he was arrested Tuesday, said Dennis Mihalopoulos, an agent with the Drug Enforcement Administration.

Police said they began investigating Acerra in early February after an informant told them the principal was using and distributing the drug.

Acerra, 50, who was in custody in lieu of bail, has an unlisted phone number, and it wasn’t clear whether he had an attorney. No one answered the door Wednesday at his modest rowhouse along a narrow alley in Allentown.

A letter was sent to parents informing them of the arrest, and teachers had spoken with the 950 students at the school where Acerra had been principal since 2000, said Bethlehem schools Superintendent Joseph Lewis.