A St. Tammany Parish school teacher and a half-dozen other people are caught up in a drug investigation carried out by a narcotics task force. Authorities announced yesterday that 51-year-old Melissa Pattison was arrested on gun and drug charges last Friday at Lyon Elementary School in Covington. A search of her home in Lacombe led to the seizure of ecstasy, LSD, marijuana, Xanax and a suspected THC lab.