Related Rule
Spain
Practice Relating to Rule 117. Accounting for Missing Persons
Section A. Search for missing persons
Spain’s LOAC Manual (1996) states that the relevant provisions relating to the dead apply also to the missing. It also states: “The belligerents shall search for the persons whose disappearance has been notified by the adverse party, who shall communicate all the relevant information concerning them.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 5.d.2.(6).
Spain’s LOAC Manual (2007) states: “Provisions concerning the dead also apply, where appropriate, to missing persons. … Each party to the conflict must endeavour to trace persons reported missing by an adverse party.” 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 5.2.d.(6).
Spain’s Law on the Victims of the Civil War and the Dictatorship (2007) states:
The public administrations, within their competence, shall facilitate the search for, localization and identification of persons who disappeared during the Civil War or during the subsequent political repression and whose whereabouts are unknown, if direct descendants of victims make such a request. 
Spain, Law on the Victims of the Civil War and the Dictatorship, 2007, Article 11(1).