COLUMBUS, Ohio — An Ohio doctor accused of ordering drug overdoses in the deaths of 25 hospital patients has sued his former employer for defamation, saying in a lawsuit that he did nothing wrong and did not deviate from hospital policy on end-of-life care.

Dr. William Husel, who is accused of murder, filed the lawsuit Thursday in Franklin County against the Columbus-area Mount Carmel Health System and its parent organization, Trinity Health Corp.

“It would not be an exaggeration to state that Dr. Husel has suffered perhaps the most egregious case of defamation in Ohio's recent history,” according to the lawsuit.

Patients died from their illnesses, not the administration of fentanyl, a powerful painkiller ordered by Husel, he said in the lawsuit.

Husel also claims he received no formal training on hospital procedures from Mount Carmel when he was hired in 2013 as a critical care physician and that he received a doctor of the year award in 2014.

Husel's lawsuit seeks more more than $50,000 in damages, along with attorney fees.

Mount Carmel and Trinity Health responded Saturday with a statement calling Husel's allegations “unfounded."

“We completed an extensive review of patient care provided by Dr. William Husel and stand by our decisions,” the statement said.

Mount Carmel officials said in January after the filing of the first of more than two dozen lawsuits regarding Husel's care that he ordered "significantly excessive and potentially fatal" doses of pain medicine for at least 27 near-death patients after families asked that lifesaving measures be stopped.

The hospital system also said then that it had fired Husel and removed nurses and pharmacists who had roles in delivering and administering pain medication Husel had ordered.

A pharmacist and nine Mount Carmel nurses sued the hospital system this month, claiming Husel did nothing wrong. Their lawsuit said hospital executives were unaware of appropriate standards of care for patients at the end of their lives.

Twenty-five Mount Carmel nurses and three pharmacists face administrative discipline by their respective state licensing boards. Husel's license to practice was suspended in January by the State Medical Board of Ohio.

He was indicted in June on 25 counts of murder and has pleaded not guilty.