An 18-year-old in Warren County is facing charges after she added liquid chemical to a teacher's coffee and the teacher consumed the beverage, police say.

According to the Warren County Sheriff's Office, a teacher at the North Warren Central School drank coffee on May 13th later determined to contain Expo cleaner, a liquid used to clean dry-erase boards.

The teacher was treated for throat irritation, then released.

Police say Sierra Heller of Chestertown had put the chemical in the coffee.

Heller was charged with third-degree assault. She is due to return to the Town of Chester Court on May 26th at 10 a.m.