provide an opportunity for public denunciation of arbitrary acts, and accountability for perpetrators; foster society’s confidence in the legal system and in the work of its authorities, legitimizing their actions; contribute to social reconciliation procedures based on the knowledge of the truth of what happened and the dignification of the victims and, ultimately, strengthen social cohesion and the rule of law.174 103. To evaluate compliance with the foregoing, the Court is able, within the sphere of its complementary and collaborative competence, to examine different aspects of the domestic investigation procedures,175 including the competence of the intervening authorities and the diligence of their actions. The latter, when it is argued that errors could have impaired the investigation as a whole so that, “with the passage of time, the possibility of obtaining and presenting pertinent evidence, which permits clarification of the facts and determination of the corresponding responsibilities, is unduly affected.”176 b.1. Obligation to investigate the facts of this case 104. This Court has established that, in light of the obligation to investigate human rights violations, “once the state authorities are aware of an incident, they must initiate, ex officio and without delay, a thorough, impartial and effective investigation […] using all available legal means and for the purpose of determining the truth.”177 105. In this case, the Court notes, first, that the initiation of the investigations into the gross human rights violations perpetrated on April 28 and 29, 1982, was not decided, ex officio; rather, it was opened as a result of the denunciation filed on January 16, 1996, by the Asociación de Familiares de Detenidos-Desaparecidos de Guatemala (FAMDEGUA) before the Trial Court of the department of Petén. The Court also notes that the State was aware of the existence of this massacre, not only because it was perpetrated by state agents, but also because, the day after the incident, the deputy mayor reported the events, and members of the army proceeded to gather up some of the corpses and bury them in a mass grave in the village cemetery. 178 106. In addition, it was not until April 18, 1996 – that is, almost 14 years after the events – that the Public Prosecution Service ordered the initiation of the corresponding criminal prosecution and decided that the necessary measures should be taken to clarify the facts. 179 This involved a flagrant delay that, of necessity, had an impact on the corresponding collection of evidence. Thus, the Court recalls that the effects of the passage of time are directly proportionate to the limitation – and, in The Special Rapporteur on the promotion of the truth, justice, reparation and guarantees of non-recurrence has stressed that criminal prosecutions in transitional processes “provide recognition to victims as rights holders. They also provide an opportunity for the legal system to establish its trustworthiness, […] strengthen the rule of law and […] contribute to social reconciliation.” Human Rights Council, Report of the Special Rapporteur on the promotion of the truth, justice, reparation and guarantees of non-recurrence, Pablo de Greiff, UN Doc. A/HRC/27/56, August 27, 2014, para. 22. See, also, United Nations Security Council, Report of the Secretary-General, The rule of law and transitional justice in conflict and post-conflict societies, UN Doc. S/2004/616, August 3, 2004, para. 39. 174 Cf. Case of the “Street Children” (Villagrán Morales et al.) v. Guatemala. Merits. Judgment of November 19, 1999. Series C No. 63, para. 222, and Case of Coc Max et al. (Xamán Massacre) v. Guatemala, supra, para. 80. 175 Cf. Case of Ibsen Cárdenas and Ibsen Peña v. Bolivia. Merits, reparations and costs. Judgment of September 1, 2010. Series C No. 217, para. 172, and Case of Bedoya Lima et al. v. Colombia. Merits, reparations and costs. Judgment of August 26, 2021. Series C No. 431, para. 128. 176 Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra, para. 177, and Case of Rosendo Cantú et al. v. Mexico. Preliminary objection, merits, reparations and costs. Judgment of August 31, 2010. Series C No. 216, para. 175. 177 Cf. Testimony of Samuel Gregorio Bracamonte, January 1996 (evidence file, folio 646), and Statement before the Public Prosecution Service of Samuel Gregorio Bracamonte on October 12, 2006 (evidence file, folio 537). 178 179 Cf. District prosecutor of the Public Prosecution Service, Decision of April 18, 1996 (evidence file, folio 78). 33