Federal investigators have concluded that supervisors at Dover Air Force Base retaliated against four civilian whistleblowers after they reported missing body parts and other failures at the mortuary that handles America’s war dead.

The Office of Special Counsel, an independent agency that investigates whistleblower complaints, said Tuesday that it has formally asked the Air Force to take harsher disciplinary action against three supervisors at the mortuary. The investigators said supervisors tried to fire two of the whistleblowers and placed others on suspension and indefinite leave.

The findings increase the pressure on Air Force Secretary Michael Donley to intervene more forcefully in the scandal at Dover, where various investigations have documented the mishandling of corpses. The Washington Post also uncovered a longtime practice of dumping incinerated partial remains of troops in a Virginia landfill.

In November, after an 18-month investigation prompted by the whistleblowers, the Air Force announced that it had disciplined — but not fired — three top supervisors at the mortuary. At the time, senior Air Force officials said there was no evidence that the whistleblowers had suffered reprisals or that the supervisors had broken any specific rules.

In response, members of Congress and veterans groups criticized Donley for not taking the problems more seriously. Defense Secretary Leon E. Panetta directed him to reconsider, suggesting that tougher punishment was warranted for the supervisors.

On Tuesday, Donley said he would appoint a two-star general to review the findings by the Office of Special Counsel. “I believe strongly there is no place for reprisal in the Air Force,” he said in a statement. “Reprisals against employees are unethical and illegal and counter to Air Force core values.”

Two of the mortuary supervisors still work at Dover.

Trevor Dean, a mortician and funeral director who served as the top civilian at the mortuary, accepted a transfer to a lesser, non-supervisory position.

Quinton “Randy” Keel, a licensed funeral director and mortician who served as division director at the mortuary, was demoted in August. He no longer works at the mortuary but has been assigned to another position at Dover Air Force Base, officials said.

Col. Robert Edmondson, who served as mortuary commander from January 2009 to October 2010, was issued a letter of reprimand for “failure in leadership,” usually a career-ending punishment for a military officer. He is still on active duty but has been reassigned.

Edmondson, Keel and Dean did not immediately respond Tuesday to requests for comment placed with the Air Force. They have previously declined to speak about the Dover investigations.

The Office of Special Counsel said it would give the Air Force one month to take action. If the Air Force does not, the Office of Special Counsel said it was prepared to pursue disciplinary action against the two civilian supervisors before the federal Merit Systems Protection Board.

The Office of Special Counsel did not release copies of its investigative report Tuesday but said it would make it public in 30 days.

Previously, the agency reported that two mortuary workers, James G. Parsons Sr., an autopsy embalming technician, and David Vance, a mortuary inspector, were fired last year but reinstated after the Office of Special Counsel intervened.

Two other mortuary employees, William D. Zwicharowski and Mary Ellen Spera, have said they were suspended or placed on leave after they disclosed wrongdoing at Dover.