Washington (CNN) -- Army Secretary John McHugh ordered a new investigation into poor record keeping and other problems at Arlington National Cemetery even as a separate investigation ended without an absolute answer to who is buried in a grave marked "Unknown."
"As the final resting place of our nation's heroes, any questions about the integrity or accountability of its operations should be examined in a manner befitting their service and sacrifice," McHugh said in a statement after signing the order directing the Army's Inspector General to begin an investigation into allegations regarding cemetery operations.
The Army IG is already in the middle of an investigation ordered by the previous secretary of the Army to review management of the cemetery.
In recent years, the cemetery -- where President Kennedy and thousands of fallen U.S. soldiers, sailors, airmen and Marines are buried -- has had a number of embarrassing problems.
In 2008, the cemetery discovered that workers inadvertently buried cremated remains at a grave site already in use. Those remains were moved to another grave site.
In 2003, as workers were digging a grave for a new burial, they discovered a casket already buried there. There was no headstone or grave marker to indicate who. Only recently, after a report by a journalist at Salon.com, did the Army take action on the problem. Over the summer, the cemetery put up a headstone on the mystery grave that reads "Unknown."
As McHugh ordered the new investigation, the Army released results of a separate investigation of problems at the cemetery. That investigation focused on the discovery of the "Unknown" grave.
A spokesman for the Military District of Washington, which conducted the review, said "Cemetery records, the MDW investigation, and the non-invasive geophysical analysis of the grave sites strongly indicate that a husband and wife, who died years apart and should have been buried in the same grave site, were instead buried in adjacent graves."
A DNA test of the remains in the two adjacent graves could prove conclusively that is what happened, but the family of the husband and wife did not wish for their remains to be disturbed. The MDW said the Army will abide by the family's wishes and has ordered a headstone to properly mark the wife's grave.
One of the problems discovered by the MDW investigation was a possible lack of adequate staffing at the cemetery. Last year Arlington conducted 4,377 burials, up more than 21 percent over the past 10 years. During that same period the number of civilian staff members has dropped nearly 19 percent. Currently the cemetery has four employees to schedule 135 to 150 funerals a week as well as maintain all grave records.
Arlington, which sits on a hill across the Potomac River from the Lincoln Memorial, has been the final resting place for America's military heroes since the Civil War, when the Union seized the estate from the family of Confederate Gen. Robert E. Lee.
McHugh hopes this new investigation will "ensure America's confidence in the operation of its most hallowed ground."