SEATTLE -- Washington Department of Health officials said Wednesday an active investigation was underway into Northwest Hospital in connection with one of its former employees now charged in federal court in Colorado for stealing the highly potent narcotic Fentanyl.

Rocky Allen, 28, is accused by federal prosecutors of drug diversion, swapping syringes of Fentanyl for syringes of other material inside hospitals. Facilities in Arizona and California caught Allen doing just that prior to his employment in Colorado, where he was ultimately charged with the crime, known as drug diversion.

Before that work, Allen worked for three months at Seattle's Northwest Hospital.

The disclosure of Allen's alleged actions led to thousands of people, including more than 1,300 in Washington, to be tested for Hepatitis A & B, and HIV.

This new investigation from the Department of Health focuses on Northwest Hospital, and whether it should have notified the state of illegal or improper activity committed by Allen while he worked there. At this point, no complaints or other issues have ever been brought up about his time at the facility.

State law requires hospitals and medical facilities notify the Department of Health of any actions that could jeopardize health.

"We had a situation where someone broke the law and had worked in a facility in Washington state," said Tim Farrell from Washington's Department of Health. "That made us feel that it was warranted to check it out."

Farrell declined to say more about the case, since it is ongoing. However, state officials said an investigation like this requires they have some reason to believe something was not done right.

"We send our folks in," continued Farrell. "They will review the systems in place on how they handle diversions."

Northwest Hospital said Allen's job was terminated for "failing to meet standards and expectations," adding that nothing took place that would have necessitated notifying the state.

Allen worked at two other medical facilities in Washington as well. It is not clear from state officials if they are being investigated.