Prosecutors charged a former nurse Thursday with abusing multiple infants in a Wisconsin hospital's intensive care unit, accusing him of bruising them and breaking their bones.

Christopher Kaphaem, 43, faces 19 felony child abuse counts involving nine infants. All but one of the counts carries a maximum sentence of six years in prison.

The 19th count, intentional child abuse causing great bodily harm, carries a maximum 25 years behind bars.

Hospital staff had documented an array of injuries to nine infants, including bruising, broken ribs, broken legs and a fractured skull.

Police began investigating reports of injuries to infants in UnityPoint Health-Meriter Hospital's infant intensive care unit in February, according to the criminal complaint. The hospital is in Madison, the state capital.

Kaphaem inflicted the injuries between March 2017 and February of this year, according to the complaint.

Investigators interviewed another nurse who took care of one of the infants Kaphaem allegedly injured, Madison's WMTV-TV reported.

"(N)ever in my 32 years of working in the NICU have I ever see anything like that,” the nurse said, according to the station.

"(N)ever in my 32 years of working in the NICU have I ever see anything like that." — Former colleague of the ex-nurse facing charges

Kaphaem's attorney didn't immediately return a message Thursday.

Investigators keyed on Kaphaem, who worked the night shift in the unit, after other nurses told them that he had cared for the babies.

They said Kaphaem often closed the door to the infants' rooms when he checked on them, ignored alarms, never asked for help and once said he was happy to work with infants because he didn't have to deal with patients talking back to him.

The complaint doesn't indicate whether investigators ever spoke with Kaphaem or discuss a possible motive.

Meriter suspended Kaphaem on Feb. 8, and state regulators suspended his license March 19.

The Centers for Medicare and Medicaid Services inspected the hospital in February, days after it suspended Kaphaem and issued a scathing report saying the facility didn't do enough to prevent the injuries.

The failure was so serious it constituted an immediate threat to patient health safety and the hospital's Medicare contract could be terminated if the problem isn't fixed, the report said.

The hospital released a statement saying the facility remains "devastated by what happened."

"While we are deeply saddened by these recent events, we are determined to learn from them, regain your confidence and serve our patients for generations to come," the statement said.

The statement also offered a bulleted list of improvements, including immediately removing Kaphaem from his job, cooperating with authorities, installing around-the-clock surveillance cameras in infant intensive care unit rooms and setting up a hotline for anyone with concerns about care in the unit.

The Associated Press contributed to this report.