Three Vermont state troopers have resigned amid an investigation into allegations relating to fake COVID-19 vaccination cards.

The former troopers — Shawn Sommers, Raymond Witkowski and David Pfindel — are suspected of having “varying roles” in a scheme to create fake vaccination cards that may violate federal law, the Vermont State Police said in a press release Tuesday.

The agency said the allegations, which were reported by other state troopers, were also referred to federal law enforcement authorities.

Col. Matthew Birmingham, director of the Vermont State Police, said in a statement that he “could not be more upset and disappointed.”

“I’m embarrassed that this situation has occurred and know that it has tarnished the reputation of the Vermont State Police,” Birmingham said. “That said, the alleged criminal conduct from these troopers does not represent the values and actions of the dedicated men and women of the Vermont State Police.”

Vermont Public Safety Commissioner Michael Schirling said in a statement that based on an initial review, there was nothing more state police leaders could have done to prevent the incident.

Sommers and Witkowski submitted their resignations on Aug. 10 after another trooper raised concerns about the men’s conduct. Pfindel resigned effective Sept. 3 after an investigation from the Department of Public Safety. 

Concerns about fake vaccine cards have become prevalent as the U.S. continues its COVID-19 vaccination campaign and vaccines become mandatory for certain jobs, venues and activities. 

In a public service alert dated March 30, the FBI warned that forging a vaccine card is illegal, as the unauthorized use of an official government agency’s seal is a federal crime.