The tusks had been cast off to a corner until 2007, when an Ethiopian businessman lobbied for them to be displayed in a glass case in a fifth-floor conference room in the Wilson Building on Pennsylvania Avenue, just three blocks from the White House. The building houses the Mayor and Council of the District of Columbia.
The tusks were moved again in August when workers had to replace wood paneling in the room -- and that's when they went missing.
According to WaPo, the tusks were in an unlocked case:
D.C. Council Chairman Phil Mendelson (D) said he did not know that the display case was unlocked and that the tusks were a gift from the Ethiopian emperor. "In hindsight, if I'd realized the value of them, and I don't necessarily mean monetary value, I would have assured there was more care in handling them," he said.
The Convention on International Trade in Endangered Species banned the sale of ivory harvested after 1989, but it is still incredibly valuable on the black market. A single pound of ivory can retail for $1,500.