66 217. The obligation to investigate human rights violations is one of the positive measures that States must adopt to guarantee the rights recognized in the Convention. 239 Thus, since its first judgment, this Court has emphasized the importance of the State’s duty to investigate and punish human rights violations, 240 which takes on particular importance given the seriousness of the crimes committed and the nature of the rights infringed. 241 218. Furthermore, the obligation to investigate, prosecute and, where appropriate, punish those responsible for human rights violations is not only derived from the American Convention; in certain circumstances and depending on the nature of the facts, it is also derived from other interAmerican instruments that establish the obligation of States Parties to investigate conduct prohibited by such treaties. In relation to the facts of this case, the State’s obligation to investigate possible acts of torture or other cruel, inhuman or degrading treatment is reinforced by the provisions of Articles 1, 6 and 8 of the Inter-American Convention against Torture, which oblige the State to “take effective measures to prevent and punish torture within the sphere of its jurisdiction,” and to “prevent and punish […] other cruel, inhuman or degrading treatment or punishment.” This obligation is applicable to Peru with the entry into force of said Convention on April 28, 1991. Likewise, the obligation to investigate is reinforced by Article I (b) of the InterAmerican Convention on Forced Disappearance of Persons, in force in Peru since March 15, 2002. 242 219. The Court notes that the specific obligations derived from the aforementioned specialized conventions are enforceable by the State from the date of deposit of the instruments of ratification of each one, and enter into force for that State, even if they were not in effect at the time the forced disappearances and other violations alleged in the instant case began to be committed. 220. Based on the arguments of the parties and the Commission, the Court will now analyze the alleged violations in relation to the investigations of the facts of the case, in the following order: 1) due diligence in the first investigative proceedings; 2) the effectiveness of the habeas corpus remedy; 3) obstacles in the investigations; 4) the lack of due diligence in the proceedings initiated after the reopening of the case, and 5) the right to know the truth. B.1. Due diligence in the initial investigative proceedings 221. The Court has already pointed out that, once a forced disappearance has occurred, it is essential that it be effectively addressed and treated as an unlawful act that may result in the imposition of sanctions on anyone who commits, instigates, conceals or in any other way participates in its perpetration. Consequently, whenever there are reasonable grounds to suspect that a person has been subjected to enforced disappearance, a criminal investigation must be initiated. 243 This obligation is separate from the filing of a complaint, since in cases of forced disappearance, international law and the general duty of guarantee, impose the obligation to investigate the case ex officio, without delay, and in a serious, objective and effective manner, so Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra, paras. 166 and 176, and Case of Rodríguez Vera et al. (Disappeared of the Palace of Justice) v. Colombia, supra, para. 436. 240 Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra, para. 166, and Case of Rodríguez Vera et al. (Disappeared of the Palace of Justice) v. Colombia, supra, para. 436. 241 Cf. Case of Goiburú et al. v. Paraguay, supra, para. 128, and Case of Rodríguez Vera et al. (Disappeared of the Palace of Justice) v. Colombia, supra, para. 436. 242 Article I(b) of the ICFDP establishes: “The States Parties to this Convention undertake to: […] b) Punish within their jurisdictions, those persons who commit or attempt to commit the crime of forced disappearance of persons and their accomplices and accessories.” 243 Cf. Case of Anzualdo Castro v. Peru, supra, para. 65, and Case of Rodríguez Vera et al. (Disappeared of the Palace of Justice) v. Colombia, supra, para. 475. 239