Lawrence Small, the head of the Smithsonian Institution, resigned this weekend, just days after the Senate voted to withhold $17 million from the agency after an audit found that Small made unauthorized payments for lavish expenses.

Small’s departure comes on the heels of an internal audit that found that he had billed the Smithsonian — a 70-percent federally financed, nonprofit, tax-exempt institution — more than a million dollars for the use of his home and made $90,000 in unauthorized expenditures.