Chapter II Definition of Terms
Section 3. For purposes of this Act, the term:
(g) "Enforced or involuntary disappearance of persons" means the arrest, detention, or abduction of persons by, or with the authorization support or acquiescence of, a State or a political organization followed by a refusal to acknowledge that deprivation of freedom or to give information on the fate or whereabouts of those persons, with the intention of removing from the protection of the law for a prolonged period of time.
Enforced disappearance - crimes against humanity
EDIT.