5 U.S.C. § 5583

(a) Under such regulations as the Director of the Office of Personnel Management may prescribe, the employing agency shall pay money due a deceased employee to the beneficiary designated by the employee under section 5582(b) of this title , or, if none, to the widow or widower of the employee. (b) The Director may by regulation prescribe the method for settlement of accounts payable under subsection (a) of this section. However— (1) accounts of employees of the government of the District of Columbia shall be paid by the District of Columbia; and (2) accounts of employees of Government corporations or mixed ownership Government corporations may be paid by the corporations.