MIAMI (WFLA) — A former nurse in Florida has been accused of tampering with fentanyl vials meant for surgery, according to the United States Department of Justice.

Officials said Catherine Shannon Dunton, 54, allegedly switched vials of liquid fentanyl citrate for saline while working as a registered nurse at an outpatient surgery center in Martin County.

Fentanyl citrate is a type of fentanyl used for surgery patients to keep them from moving during the procedures and alleviate their pain.

“Dunton removed liquid fentanyl from vials, refilled them with saline, and returned the adulterated vials to their location for use during surgeries,” the DOJ said.

Friday, a federal grand jury charged Dunton with tampering with medical-grade fentanyl. If found guilty, the former nurse could spend 10 years in federal prison.