45 where the victim might be found deprived of liberty. 220 In this case, that obligation was reinforced by the fact that the victims were children at the time of the events, one of them in her early infancy, so that the State had the obligation to ensure they were found as soon as possible. The legal rights involved in the investigation make it obligatory to redouble efforts as regards the measures that must be taken to fulfill this objective, because the passage of time has a directly proportionate relationship to the limitations to – and, in some cases, the impossibility of - obtaining evidence and/or testimony, making it difficult and even rendering ineffective or invalid, the probative measures taken in order to elucidate the facts investigated,221 identify the possible authors and participants, and determine possible criminal responsibilities. Despite the foregoing, national authorities are not exempt from making all necessary efforts to comply with their obligation to investigate.222 Inaction or negligent action on the part of the State and its bodies is not compatible with its obligations under the American Convention, particularly if essential human rights are at stake.223 Thus, the States must provide the corresponding authorities with the necessary logistic and scientific resources to gather and process evidence and, in particular, the authority to access pertinent documentation and information to investigate the facts denounced and obtain indications or evidence of the whereabouts of the victims.224 140. It is also important to recall that, in its case law, the Court has considered the content of the right to know the truth, particularly in cases of forced disappearance. In the Case of Velásquez Rodríguez v. Honduras the Court affirmed the “right of the next of kin of the victim to know his/her fate and, if it were the case, where the remains are.”225 In such cases it is understood that the next of kin of disappeared persons are victims of the facts that constitute forced disappearance, which grants them the right to have the facts investigated and that those responsible be tried and, where appropriate, punished.226 The right to know the truth of the next of kin of victims of serious human rights violations forms part of the right of access to justice.227 A. Duty to initiate an investigation ex officio 141. According to the evidence, on May 31, 1996, the representatives of the Search Association filed a complaint with the Office of the Human Rights Ombudsman in which it set out a total of 141 cases of children who had been victims of forced disappearance, all in the context of the Salvadoran armed conflict.228 The Ombudsman’s Office issued a decision on March 30, 1998, under file number SS-0449-96, referring to seven cases illustrative of the forced disappearance of children during the armed conflict, and indicating that members of the Armed Forces of El Salvador were responsible for 220 Cf. Case of Anzualdo Castro v. Peru, supra, para. 134, and Case of Contreras et al. v. El Salvador, supra, para. 145. Cf. Case of Heliodoro Portugal v. Panama. Preliminary objections, merits, reparations and costs. Judgment of August 12, 2008. Series C No. 186, para. 150, and Case of Osorio Rivera and Family v. Peru, supra, para. 185. 221 Cf. Case of Anzualdo Castro v. Peru, supra, para. 135, and Case of Palma Mendoza et al. v. Ecuador. Preliminary objection and merits. Judgment of September 3, 2012. Series C No. 247, para. 94. 222 Cf. Case of Garibaldi v. Brazil, Preliminary objections, merits, reparations and costs. Judgment of September 23, 2009. Series C No. 203, para. 130, and Case of Contreras et al. v. El Salvador, supra, para. 145. 223 224 Cf. Case of Tiu Tojin v. Guatemala, supra, para. 77, and Case of Osorio Rivera and Family v. Peru, supra, para. 182. 225 Case of Velásquez Rodríguez v. Honduras. Merits, supra, para. 181. 226 Cf. Case of Blake v. Guatemala. Merits, supra, para. 97, and Case of Radilla Pacheco v. Mexico, supra, para. 180. Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra, para. 181; Case of Anzualdo Castro v. Peru, supra, para. 118, and Case of Gelman v. Uruguay, supra, para. 243. 227 Cf. Telefax issued by the Asociación Pro-Búsqueda sent to the Office of the Human Rights Ombudsman on May 31, 1996 (evidence file, volume IV, annex 7 to the submission of the case, folio 1875), and list of cases presented by the Asociación Pro-Búsqueda to the Office of the Human Rights Ombudsman on May 31, 1996 (file of proceedings before the Commission, volume II, folios 982 to 985). 228