JACKSONVILLE, Fla. (AP) — A nurse working at a Florida hospital has pleaded guilty to stealing fentanyl and replacing the powerful pain medication with saline.

Court records show 35-year-old Monique Carter pleaded guilty Wednesday in Jacksonville federal court to tampering with a consumer product. She faces up to 10 years in prison.

According to the plea agreement, Carter was working at a Jacksonville hospital in September when a pharmacist examining the fentanyl inventory found a syringe missing a tamper-proof cap.

A supervisor reviewing hospital records found a pattern of Carter checking out doses of fentanyl for patients but then canceling the transactions and checking syringes back into the hospital’s inventory.