27 considered that the due diligence in the investigation implies that it be carried out ex officio, without delay, and in a serious, impartial, and effective manner.85 77. Based on the aforementioned, the State shall guarantee, as a way of guaranteeing that the investigation started before the courts of the ordinary jurisdiction (supra para. 20) be carried out with due diligence86 (supra para. 69), that the authorities in charge of the investigation have within their reach and uses all the means necessary to promptly carry out all those actions and inquiries essential to clarifying the fate of the victims and identifying those responsible for the forced disappearance.87 For this, the State will guarantee that the authorities in charge of the investigation have the logistic and scientific resources necessary to recollect and process evidence, and more specifically, that he is allowed access to the documents and information relevant to the investigation of the facts denounced and that they be able to obtain evidence of the locations of the victims. In this sense, it is important to reiterate that in the case of violations to human rights, state authorities cannot hide behind mechanisms such as official secrets or confidentiality of the information or behind reasons of public interest or national security, to justify not providing the information required by the judicial or administrative authorities in charge of the investigation or pending proceedings.88 78. Likewise, the State must guarantee that the authorities in charge of the investigation take into account the systematic patterns that allowed the commission of grave violations to human rights in the present case,89 so that the object of the investigation be carried out taking into account the complexity of those facts, the context in which they occurred90 and the patterns that explain their commission, avoiding omissions in the gathering of evidence and in the follow-up of logical lines of investigation.91 Legal classification applicable in the investigation, trial, and possible punishment of the offenses committed in this case 78. The Court observes that the facts of the present case started occurring before the definition of the crime of forced disappearance of persons in the Guatemalan 85 Cfr. Case of the Serrano Cruz Sisters v. El Salvador. Merits, Reparations, and Costs. Judgment of March 1, 2005. Series C No. 120, para. 88; Case of García Prieto et al. v. El Salvador, supra note 82, para. 101; and Case of Heliodoro Portugal v. Panama, supra note 17, para. 144. 86 Cfr. Inter-American Convention on Forced Disappearance of People, Article X and International Convention for the Protection of all people against forced disappearances. 87 Cfr. Case of Velásquez Rodríguez v. Honduras, supra note 20, para. 174; Case of the Serrano Cruz Sisters v. El Salvador, supra note 85, para. 83; Case of García Prieto et al. v. El Salvador, supra note 82, para. 101; and Case of Heliodoro Portugal v. Panama, supra note 17, para. 144. 88 Cfr. Case of Myrna Mack Chang v. Guatemala, supra note 15, para. 180 and 181, and Case of La Cantuta v. Peru, supra note 84, para. 111. 89 Cfr. Case of La Rochela Massacre v. Colombia, supra note 12, para. 156. 90 Cfr. Case of the Serrano Cruz Sisters v. El Salvador, supra note 85, para. 88 and 105, and Case of La Rochela Massacre v. Colombia, supra note 12, para. 157. 91 Cfr. . Case of La Rochela Massacre v. Colombia, supra note 12, para. 157.