CONCORD, N.H. (AP) — A New Hampshire hospital has agreed to pay $300,000 to resolve allegations that it violated federal law by failing to keep accurate records of controlled substances, including opioids, the U.S. attorney's office said.

The Drug Enforcement Administration began an investigation last year at Catholic Medical Center in Manchester, finding that a nurse anesthetist diverted liquid fentanyl left over from medical procedures instead of safely discarding it, and that she falsified disposal records, the U.S. attorney's office said Monday. The investigation also showed that the nurse stole controlled substances about once a day for a year.

The nurse pleaded guilty last month to tampering with consumer products, admitting she replaced the liquid fentanyl meant for an operating room patient with saline and another drug. She awaits sentencing.

A DEA audit of the hospital's records showed that it did not accurately reflect its inventory for seven controlled substances, including fentanyl, because it possessed greater quantities than its records indicated for those drugs, the U.S. attorney's office said.

Catholic Medical Center did not admit to liability, the U.S. attorney's office said. It cooperated with the investigation and has taken significant steps to improve its controls and procedures against future theft and diversion of controlled substances, the office said.

“Catholic Medical Center is committed to adhering to the highest standards and maintaining a strong drug diversion prevention program,” the hospital said in a statement. “Upon discovery of this incident, CMC took immediate action, promptly notifying federal and state authorities and cooperating fully throughout their investigations.”