CHARLESTON, W.Va. (AP) — A third lawsuit was filed Monday involving the deaths of patients over wrongful insulin injections at a West Virginia veterans hospital.

Charleston attorney Tony O’Dell filed the federal lawsuit in the death of John William Hallman. The 87-year-old Navy veteran died at the Louis A. Johnson VA Medical Center in Clarksburg in June 2018. The lawsuit was filed on behalf of Hallman's son and daughter and seeks unspecified damages.

Five months after he died, Hallman’s death certificate was amended and his immediate cause of death was listed as “unexplained hypoglycemia,” or low blood sugar. The lawsuit alleged an unidentified employee had given Hallman a shot of insulin despite no physician’s order being issued.

The lawsuit asserts that prior to Hallman's death, the night shift on the same hospital floor “experienced sudden severe unexplained patient decline leading to patient death on at least 9 occasions.”

O’Dell also filed a lawsuit in April on behalf of the widow of George Nelson Shaw Sr., an 81-year-old retired member of the Air Force who also died at the hospital in April 2018. That suit said an autopsy performed on Shaw found four insulin injection sites on both arms and one leg.

A similar lawsuit was filed in March by a woman whose father, former Army Sgt. Felix Kirk McDermott, 82, also died at the hospital in April 2018.

Federal prosecutors are probing the deaths of up to 11 patients at the hospital. Attorneys representing the families of men who died say the deaths of McDermott and Shaw have been ruled homicides.

Bill Powell, the U.S. attorney for northern West Virginia, has said the investigation is a “top priority.” But U.S. Sen. Joe Manchin of West Virginia told Attorney General William Barr in a letter last year that he had “grave concerns over the pace of the investigation.”

The Democrat said VA officials had told him a “person of interest” was no longer in contact with any veterans at the facility. The VA inspector general told Manchin’s office about the opening of a medical and criminal investigation of the hospital in July 2018.

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