The daughter of a decorated veteran who died suddenly of an insulin overdose at a Veterans Affairs hospital in West Virginia over a year ago -- and whose death has been dubbed a homicide -- filed a lawsuit Monday against VA Secretary Robert Wilkie.

Melanie Proctor said a "widespread system of failures" at the Louis A. Johnson VA Medical Center in Clarksburg ultimately resulted in the death of her 82-year-old father, former Army Sgt. Felix Kirk McDermott.

DAUGHTER OF VET WHO DIED IN VA HOSPITAL UNDER SUSPICIOUS CIRCUMSTANCES SPEAKS OUT, 'STILL WAITING' FOR ANSWERS

McDermott suffered from dementia following a stroke a few years prior and died suddenly on April 9, 2018, at the VA hospital. The latter years of his life had been spent battling heart disease, hypertension and chronic obstructive pulmonary disease (COPD). Three days before his death, he was admitted to the hospital with pneumonia after he got food caught in his lung, but he appeared to be rebounding, according to Proctor.

It wasn't until a few months later -- when investigators with the VA watchdog's office let her know his death was marked by some suspicious circumstances -- that she let them exhume his body.

An autopsy revealed that McDermott received a dose of insulin to his abdomen, which could be deadly to someone who did not have diabetes. Hospital records did not indicate that doctors had ordered any insulin for McDermott; the shot caused his blood sugar level to take a deadly dive.

The lawsuit, which seeks unspecified damages, alleges an unnamed employee who administered the injection was not qualified to be a nursing assistant and that hospital staff failed to take appropriate action to stop the employee from giving the shots.

In total, 11 veterans who died at the same hospital appeared to have received lethal doses of insulin despite not being treated for diabetes or high blood sugar, according to reports.

The VA is the government’s second-largest department and responsible for 9 million military veterans.

Sen. Joe Manchin, D-W.V., announced that the VA inspector general told his office they were opening a medical and criminal investigation into the hospital in July 2018 and had identified a person of interest.

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The Associated Press contributed to this report.