GRAND RAPIDS, Mich. (WOOD) — A Kalamazoo County nurse has pleaded guilty to tampering with pain medication for patients, court documents say.

Alison Renee Marshall, 45, of Sturgis pleaded guilty to tampering with vials of liquid fentanyl at the hospital where she worked. During July and August in 2020, Marshall, a registered nurse, removed liquid fentanyl and replaced it with saline solution. It was noticed in August by another nurse working in the interventional radiology unit, according to court documents.

The hospital staff’s pharmacist did an investigation and found that several fentanyl vials had caps that had been glued back on. FDA lab tests showed that the vials were diluted, only containing 3% or less of the drug, court documents say.

Marshall admitted to both hospital staff and federal court that she was taking the fentanyl for her own use and knew that patients would be given the diluted fentanyl, according to court documents.

She faces up to 10 years in federal prison and is scheduled for sentencing on Sept. 22.