pointed out that the duty to investigate is an obligation of means and not of result that must be assumed by the State as its legal duty and not as a simple formality preordained to be ineffective or as a step that depends upon the initiative of the victims or their next of kin or upon their offer of proof.69 The investigation must also be serious, objective and effective and directed to determine the truth and to the pursuit, arrest, and eventual prosecution and punishment of the perpetrators.70 Due diligence requires the investigating body to carry out every measure and inquiry necessary to obtain the required result.71 68. The State recognized its international responsibility in this case for the violations of the rights of judicial guarantees and to judicial protection of Mr. Garzón Guzmán and his next of kin. However, the Court deems it relevant to analyze the violation of these irghts to establish their scope in this specific case. Thus, the Court will make reference to: 1) the duty of the State to undertake de oficio and conduct the investigations with due diligence; 2) the omission of the duty of due diligence in the search for Mr. Garzón Guzmán and the alleged violation of the duty to adopt provisions of domestic law, and 3) the guarantee of a reasonable time and the right to know the truth. B.1 Duty to undertake de oficio and conduct the investigations with due diligence 69. With respect to the duty to undertake an investigation de oficio, the Court has stated that, whenever there is reason to believe that a person has been forcibly disappeared, the State must undertake a criminal investigation, even without a formal complaint. 72 This obligation is independent of whether there exists a complaint since, in cases of forced disappearance, international law and the general duty to guarantee impose upon the States the obligation to investigate the case ex officio, without delay and in a serious, impartial and effective manner and that it does not depend upon the initiative of the victim or his family members or upon their offer of proof.73 70. It has been shown in this case that the next of kin of Mr. Garzón Guzmán informed the State authorities regarding his disappearance in the days following the occurrence of the events. The State, therefore, had the obligation to undertake an investigation de oficio, independent of whether a formal compaint had been filed. 71. The Court also finds that, although a formal complaint was filed on November 16, 1990 and that there were numerous public complaints and press reports in 2003 (supra paras. 49 and 51), more than 20 years had elapsed before a judicial investigation was opened to establish the facts of the case. This occurred only because the Truth Commission had begun Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra, para. 177 and Case of Guachalá Chimbo et al. v. Ecuador. Merits, Reparations and Costs, supra, para. 200. 69 Cf. Case of Juan Humberto Sánchez v. Honduras. Preliminary Objection, Merits, Reparations and Costs. Judgment of June 7, 2003. Series C No. 99, para. 127 and Case of Carvajal Carvajal et al. v. Colombia. Merits, Reparations and Costs. Judgment of March 13, 2018. Series C No. 352, para. 102. 70 Cf. Case of the Serrano Cruz Brothers v. El Salvador. Merits, Reparations and Costs. Judgment of March 1, 2005. Series C No. 120, para. 83 and Case of Carvajal Carvajal et al. v. Colombia, supra, para. 102. 71 Cf. Case of Anzualdo Castro v. Peru. Preliminary Objection, Merits, Reparations and Costs, supra, para. 65, and Case of Tenorio Roca et al. v. Peru. Preliminary Objections, Merits, Reparations and Costs, supra, para. 168. In addition, Article 12(2) of the International Convention for the Protection of All Persons from Enforce Disappearance states: “Where there are reasonable grounds for believing that a person has been subjected to an enforced disappearance, the authorities referred to in paragraph 1 shall undertake an investigation, even if there has been no formal complaint.” 72 Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra, para. 177 and Case of Tenorio Roca et al. v. Peru. Preliminary Objections, Merits, Reparations and Costs, supra, para. 168. 73 18