Chief of the Smithsonian resigns

Departure comes amid controversy over unauthorized spending on items such as private jet travel.

The Smithsonian Institution announced Monday that its top official, Secretary Lawrence Small, has resigned amid criticism about his expenses.

Small resigned over the weekend, with the decision unanimously accepted Sunday by the Smithsonian's Board of Regents, the Associated Press reported.

Cristian Samper, director of the Smithsonian's National Museum of Natural History, has been appointed acting secretary while the regents conduct a nationwide search for a permanent replacement. An internal audit in January found that Small had made $90,000 in unauthorized expenses, including private jet travel and expensive gifts.