109 […] Even though [the State] has not ratified said Convention, the Court believes that the nonapplicability of statutes of limitations to crimes against humanity is a norm of General International Law (ius cogens), which is not created by said Convention, but it is acknowledged by it. Hence, [the State] must comply with this imperative rule. 226. Therefore, further to its duty to investigate and, if appropriate, punish the guilty parties, the State is required to remove all obstacles –both factual and legal– contributing to impunity, and use all available means to expedite the investigation and the relevant proceedings, thus preventing the recurrence of acts as serious as those under analysis in the case at hand. The State may not rely upon any domestic law or regulation to justify its failure to comply with the Court’s order to investigate and, if appropriate, criminally punish the parties responsible for the La Cantuta events. Particularly, as has been the case ever since the Court’s judgment in the case of Barrios Altos v. Perú, the State may never apply amnesty laws –which will produce no effects in the future (supra para. 152)–, raise the statute of limitations, non-ex post facto nature of criminal laws or res judicata defenses, or rely upon the principle of double jeopardy (supra para. 182), or resort to any other similar measure designed to eliminate responsibility in order to escape its duty to investigate and punish those responsible.180 Accordingly, as the case may be, the relevant investigations need to be opened against all parties investigated, convicted, or acquitted or whose cases were dismissed, in a military criminal proceeding. 227. Additionally, in line with the arguments above (supra paras. 159 and 160), further to the general obligation to respect laid down in Article 1(1) of the American Convention, Perú is to continue to adopt all judicial and diplomatic measures required in order to prosecute and, if appropriate, punish, all parties responsible for the violations committed in this case, and to continue to insist on the requests for extradition under the applicable domestic or international law rules. Furthermore, based on the effectiveness of the collective protection mechanism established under the Convention, the States Parties to the Convention are required to cooperate with each other in order to put an end to the impunity existing for the violations committed in the case at hand by prosecuting and, if appropriate, punishing, those responsible therefor. 228. Lastly, as has been the case so far, the State is required to guarantee to the victims’ next of kin full access and procedural capacity at all stages of and before all courts involved in such investigations and proceedings, pursuant to the domestic law and the provisions of the American Convention.181 Furthermore, the outcome thereof is to be published by the State in order that the Peruvian society may learn the truth of the facts of the case at hand. b) Search and burial of the remains of the disappeared persons 229. In the instant case, the Court has established that Hugo Muñoz-Sánchez, Dora Oyague-Fierro, Marcelino Rosales-Cárdenas, Armando Richard Amaro-Cóndor, Robert Edgar Teodoro-Espinoza, Heráclides Pablo-Meza, Juan Gabriel Mariños-Figueroa and Felipe FloresChipana are still disappeared (supra. 80(16)). 230. Moreover, the Court has proven that during the exhumations in Cieneguillas and Huachipa, bone remains and victims’ belongings were found, but it was not able to prove 180 Cf. Case of Almonacid-Arellano et al., supra note 6, para. 154. 181 Cf. Case of Montero-Aranguren et al. (Detention Center of Catia), supra note 97, para. 139; Case of Baldeón-García, supra note 163, para. 199; and Case of Blanco-Romero et al., supra note 100, para. 97.