Federal investigators are probing a series of suspicious deaths at a Veterans Affairs hospital in West Virginia, a situation that congressional lawmakers have labeled “incredibly disturbing.”

The potential crimes came to light after the family of one of the victims filed a wrongful death suit against VA alleging that their loved one’s death came as the result of an unneeded, fatal insulin dose while at the Louis A. Johnson VA Medical Center in Clarksburg.

The lawsuit alleges that VA officials did not take appropriate precautions and provide appropriate oversight to prevent harm to retired Army Sgt. Felix Kirk McDermott, 82, who died in April 2018. A copy of an Armed Forces Medical Examiner report provided by the West Virginia law firm Tiano O’Dell (which is representing McDermott’s family) ruled the death a homicide. McDermott’s health care plan did not include any insulin injections, and he was described “demonstrating clinical improvement” prior to his death.

Sen. Joe Manchin, D-W.Va. and a member of the Senate Veterans’ Affairs Committee, said in a statement this week that he has been briefed on at least 11 suspicious deaths at the facility around the same time frame.

“These crimes shock the conscience and I’m still appalled they were not only committed but that our veterans, who have sacrificed so much for our country, were the victims,” he said. “These families and loved ones deserve answers as soon as possible and I will make sure they get them.”

VA officials have said the investigation does not involve any current department staffers at the hospital, and leadership is cooperating with law enforcement and inspector general investigations.

They added that new safeguards have been put in place “to ensure the safety of each and every one of our patients.”

House Veterans’ Affairs Committee Chairman Mark Takano, D-Calif., said he’ll also demand a full accounting of what happened at the hospital.

“If VA was aware, it must hold supervisors accountable for failing to protect veterans and must take decisive action now to prevent such appalling incidents in the future,” he said in a statement.

Officials from the VA Inspector General’s office did not offer any details on the investigation, saying only that they are working with law enforcement on the next steps. The suspected attacker in the case has not been named.