31 USC 3305 - Audits of depositaries

The Secretary of the Treasury, or an officer, employee, or agent designated by the Secretary, may audit a depositary of public money. For uniformity and accuracy in accounts and safety of public money, an individual conducting an audit shall audit a depositarys
(1) books;
(2) accounts;
(3) returns; and
(4) public money on hand and the way the money is kept.