34 C.F.R.  §300.515.  Surrogate parents.

(a) General. Each public agency shall ensure that the rights of a child are protected if--

(1) No parent (as defined in Sec. 300.20) can be identified;
(2) The public agency, after reasonable efforts, cannot discover the whereabouts of a parent; or
(3) The child is a ward of the State under the laws of that State.