Law enforcement agencies should investigate Defense Secretary Donald Rumsfeld (search) and FBI agents for possessing mementos from the sites of the Sept. 11 terrorist attacks, a group of attorneys said Monday.

The National Whistleblower Center (search) made the request because an inquiry found Rumsfeld has a piece of the airplane that flew into the Pentagon inside his office. The Justice Department's inspector general also discovered that 13 FBI agents had taken rubble, debris and items such as flags and a Tiffany crystal globe paperweight from Ground Zero at the World Trade Center.

Defense Department spokesman Eric Ruff rejected any suggestion of impropriety.

"It's not a souvenir; it is a memento on display in Secretary Rumsfeld's office," said Ruff. "It's hard to imagine there's something wrong in trying to remind people of what happened on 9/11."

Rumsfeld "may have violated the federal conversion statute," the Whistleblower Center wrote Attorney General John Ashcroft (search).

The center, which represents federal employees who face retaliation for reporting possible wrongdoing inside the government, also said authorities in New York state should look into the actions of the FBI agents who took items.