37 136. 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. Thus, since its first judgment, this Court has emphasized the importance of the state's obligation to investigate and punish human rights violations,212 which acquires particular importance in light of the gravity of the crimes committed and the nature of the rights violated 213. This obligation also arises from other Inter-American instruments. Thus, in cases of forced disappearances, the obligation to investigate is reinforced by Article I(b) of the Inter-American Convention on Forced Disappearance of Persons,214 and in cases of torture it is reinforced by Articles 1, 6, and 8 of the Inter-American Convention for Prevent and Punish Torture 215. 137. Faced with the arguments made by the parties and the Commission on the rights to judicial guarantees and protection, this Court will examine: (1) the duty to initiate an investigation ex officio, and (2) due diligence in investigations. B.1 Duty to initiate an investigation ex officio 138. Whenever there are reasonable grounds to suspect that a person has been subjected to enforced disappearance, an investigation must be launched ex officio, without delay, and in a serious, impartial and effective manner.216 This obligation is independent of the filing an individual complaint, since in cases of forced disappearances international law and the general duty to guarantee rights, impose the obligation to investigate the case ex officio, without delay, and in a serious, impartial, and effective manner, in such a way that it does not depend on the procedural initiative of the victim or their relatives or on the private contribution of evidentiary elements.217 Likewise, Article 8 of the Inter-American Convention to Prevent and Punish Torture establishes that the States parties shall guarantee: any person making an accusation of having been subjected to torture within their jurisdiction shall have the right to an impartial examination of his case. Likewise, if there is an accusation Cf. Case of Velásquez Rodríguez v. Honduras. Merits. Judgment of July 29, 1988. Series C No. 4, para. 166, and Case of Alvarado Espinoza et al. v. Mexico. Merits, Reparations and Costs. Judgment of November 28, 2018. Series C No. 370, para. 212. 213 Cf. Case of Goiburú et al. v. Paraguay. Merits, Reparations and Costs. Judgment of September 22, 2006. Series C No. 153, para. 128, and Case of Alvarado Espinoza et al. v. Mexico. Merits, Reparations and Costs. Judgment of November 28, 2018. Series C No. 370, para. 212. 214 Article I(b) of the Inter-American Convention on Forced Disappearance of Persons establishes: “The States Parties to this Convention undertake: [...] b) To punish, within their jurisdictions, those who commit or attempt to commit the crime of forced disappearance of persons and their accomplices and accessories.” 215 Article 1 of the Inter-American Convention to Prevent and Punish Torture establishes: “The States Parties undertake to prevent and punish torture in accordance with the terms of this Convention.” Article 6 of that same Convention establishes: “In accordance with the terms of Article 1, the States Parties shall take effective measures to prevent and punish torture within their jurisdiction. The States Parties shall ensure that all acts of torture and attempts to commit torture are offenses under their criminal law and shall make such acts punishable by severe penalties that take into account their serious nature. The States Parties likewise shall take effective measures to prevent and punish other cruel, inhuman, or degrading treatment or punishment within their jurisdiction.” Article 8, for its part, establishes: “The States Parties shall guarantee that any person making an accusation of having been subjected to torture within their jurisdiction shall have the right to an impartial examination of his case. Likewise, if there is an accusation or well-grounded reason to believe that an act of torture has been committed within their jurisdiction, the States Parties shall guarantee that their respective authorities will proceed properly and immediately to conduct an investigation into the case and to initiate, whenever appropriate, the corresponding criminal process. After all the domestic legal procedures of the respective State and the corresponding appeals have been exhausted, the case may be submitted to the international fora whose competence has been recognized by that State.” 216 Cf. Case of Anzualdo Castro v. Peru. Preliminary Objection, Merits, Reparations and Costs. Judgment of September 22, 2009. Series C No. 202, para. 65, and Case of Alvarado Espinoza et al. v. Mexico. Merits, Reparations and Costs. Judgment of November 28, 2018. Series C No. 370, para. 215. 217 cf. Case of Velásquez Rodríguez v. Honduras. Merits. Judgment of July 29, 1988. Series C No. 4, para. 177, and Case of Alvarado Espinoza et al. v. Mexico. Merits, Reparations and Costs. Judgment of November 28, 2018. Series C No. 370, para. 240. 212