The principal of Nitschmann Middle School in Bethlehem sold crystal methamphetamine to police informants three times this month, once in his school office, police say. John Acerra, 50, of 832 Chestnut St., Allentown, was arrested Tuesday in his office, where police found meth on his desk, according to arrest papers filed by Bethlehem police. One police informant told officers that Acerra used and sold crystal meth for at least five months before his arrest, the papers say.Acerra faces felony charges of possession with intent to deliver meth and delivery of the drug and related charges. He is in Lehigh County...