Members of the American Legion listen to U.S. Veterans Affairs Secretary Robert McDonald apologize for misrepresenting his military record during the legion's annual conference at the Washington Hilton, Feb. 24, 2015, in Washington. Chip Somodevilla/Getty Images

A Senate probe into a Department of Veterans Affairs medical center in Wisconsin has uncovered serious and systemic flaws in a VA inspector general’s office, USA Today reported. The Senate concluded that those problems could have contributed to otherwise preventable tragedies, including the death of one Marine Corps veteran.

The internal agency is tasked with independently investigating complaints regarding the Tomah, Wisconsin, facility, but the way it handled its most recent report showed signs that “the inspector general ... had lost the sense of what its true mission was,” said Sen. Ron Johnson, R-Wis., who chairs the Senate Homeland Security and Governmental Affairs Committee that conducted the investigation.

The flaws that the Senate uncovered in the inspector general's office were “systemic,” Johnson told USA Today, which obtained the 350-page Senate report containing the findings of its investigation.

After the inspector general’s office carried out a two-year review of the Wisconsin facility, it decided not to release its findings, which included the discovery that two providers, including a physician dubbed Candy Man for all the pills he prescribed, were dispensing narcotics at a concerning rate. Still, the inspector general’s report did not identify any wrongdoing.

Five months after the inspector general’s office decided to close the case instead of publicly releasing the report, Jason Simcakoski, a veteran of the Marine Corps, died at the age of 35. The cause was “mixed drug toxicity.” Just days before, David Houlihan, the Candy Man, had prescribed Simcakoski his 15th drug.

Although other agencies could have done more to step in and address these problems, it was the inspector general office’s failings that the Senate pinpointed as the most egregious.

“Perhaps the greatest failure to identify and prevent the tragedies at the Tomah VAMC was the VA Office of Inspector General’s two-year health care inspection of the facility,” the Senate report said.

The failings documented in this latest Senate probe are not unique in the realm of Veterans Affairs. The VA’s medical services, for example, are plagued by notoriously long wait times.

For months, the inspector general’s office declined to make public some 140 investigations into healthcare at the VA and 77 investigations into wait times, rather than making those findings public, according to an investigation by USA Today published in February.

Last week, Veterans Affairs Secretary Bob McDonald compared veterans’ waits to see doctors to Disneyland visitors waiting in line for a ride. He has since been widely excoriated as belittling veterans and poking fun of the deplorable ways they are often treated in the United States.

“The American Legion agrees that the VA secretary's analogy between Disneyland and VA wait times was an unfortunate comparison because people don't die while waiting to go on Space Mountain,” said American Legion National Commander Dale Barnett. “We also disagree with the substance of his comment because wait times are very important to not just the satisfaction quotient, but in some cases the veterans’ health.”

A new inspector general, Michael Missal, took over the VA’s office in early May, but those charged with investigating healthcare have not changed. John Daigh, the doctor who decided not to release the office's report on Tomah, is still the assistant inspector general for healthcare inspections, according to a Department of Veterans Affairs website.