A public high school teacher nabbed in a heroin sting returned to school for the rest of the day before she was suspended with pay, Pittsburgh police said.

Mary Steck, 51, taught science at Perry Traditional Academy. She is charged with possession of heroin and possession of drug paraphernalia.

Steck's neighborhood was under surveillance after a resident complained of drug activity, police said. Steck's vehicle was stopped Wednesday about 1:10 p.m. after a man got out and appeared to buy drugs.

Police saw a syringe sticking out of Steck's purse and later found two stamp bags of heroin.

Police let Steck leave, but notified school officials. A Pittsburgh Public Schools spokeswoman said Steck was suspended about five minutes before school ended that day.