must be taken to achieve its objective, because the passage of time has a direct bearing on the limitation – and in some cases, the impossibility – of obtaining evidence and/or testimony making it difficult, or even useless or ineffective, to implement probative measures in order to clarify the facts that are under investigation, to identify the possible perpetrators and participants, and to determine the eventual criminal responsibilities. 203 The investigation must be conducted using all available legal means and be aimed at determining the truth and the pursuit, capture, prosecution, and eventual punishment of all the masterminds and perpetrators of the facts, especially when State agents are involved. 204 136. The Court also recalls that, in certain circumstances and depending on the nature of the facts, the obligation to investigate, prosecute and, as appropriate, punish those responsible for violations of human rights is revealed in other inter-American instruments that establish the States Parties’ obligation to investigate the conduct prohibited by those treaties. 205 Regarding the facts of this case, Article 1(b) of the Inter-American Convention on Forced Disappearance imposes on States the obligation “to punish within their jurisdictions, those persons who commit or attempt to commit the crime of forced disappearance of persons and their accomplices and accessories.” Therefore, according to this Court’s case law, in cases of forced disappearance, the State’s obligation to open an investigation ex officio is also derived from that Convention for the States that are a party to it. 206 These specific obligations may be require of the State as of the date that it deposits its instrument of ratification (supra para. 25), even if they were not in force when the forced disappearance began. 207 137. Taking into account the foregoing criteria, the Court will now analyze the State's obligation to conduct an investigation ex officio; the effectiveness of the applications for habeas corpus filed in 1997 and the special investigation procedure, and due diligence and compliance with the principle of reasonable time in the investigations conducted into the disappearance of Edgar Fernando García. 1. Obligation to open an investigation ex officio 138. The Court recalls that whenever there is a reasonable motive to suspect that a person has been subjected to forced disappearance, a serious, impartial and effective investigation must be opened ex officio, without delay. 208 This Court has indicated that it is essential that the prosecuting and judicial authorities take prompt and immediate action, ordering the timely and necessary measures to determine the victim’s whereabouts or the place where 203 Cf. Case of Heliodoro Portugal v. Panama, supra, para. 150, and Case of González Medina and family members v. Dominican Republic, supra, para. 218. 204 Cf. Case of the Pueblo Bello Massacre v. Colombia. Merits. Judgment of January 31, 2006. Series C No. 140, para. 143, and Case of the Río Negro Massacres v. Guatemala, supra, para. 192. 205 Cf. Case of the Miguel Castro Castro Prison v. Peru. Merits, reparations and costs. Judgment of November 25, 2006. Series C No. 160, paras. 276, 377, 378 and 379, and Case of the Río Negro Massacres v. Guatemala, supra, para. 222. 206 Cf. Case of Radilla Pacheco v. Mexico, supra, paras. 142 and 143, and Case of the Río Negro Massacres v. Guatemala, supra, para. 223. 207 Cf. Case of the Miguel Castro Castro Prison v. Peru, supra, para. 377; Case of the Las Dos Erres Massacre v. Guatemala. Preliminary objection, merits, reparations and costs. Judgment of November 24, 2009. Series C No. 211, para. 137, and Case of the Massacres of El Mozote and nearby places v. El Salvador, supra, para. 246. 208 Cf. Case of Anzualdo Castro v. Peru, supra, para. 65, and Case of the Río Negro Massacres v. Guatemala, supra, para. 223. 48