47 204 toward the determination of the truth. In that same vein, the Court has found that the State has the duty to ensure that everything necessary is done to learn the truth about what happened and for those responsible to be 205 206 punished, and involving every State institution. The Court has also said that the authorities should adopt all 207 reasonable measures to guarantee the necessary probative material in order to carry out the investigation. 233. The duty to investigate, like the duty to prevent, is not breached merely because the investigation does not produce a satisfactory result. Nevertheless, it must be undertaken in a serious manner and 208 not as a mere formality preordained to be ineffective, or as a step taken by private interests that depends upon 209 the initiative of the victim or his family or upon their offer of proof. 234. Specifically with respect to the content of the State’s obligation to investigate complaints of forced disappearance of persons, the Commission finds it pertinent to recall that the Court has held that “faced with the particular gravity of such offenses and the nature of the rights harmed, the prohibition of the forced disappearance of persons and the corresponding obligation to investigate and punish those responsible has attained 210 the status of jus cogens.” Hence, whenever there are reasonable motives to suspect that a person has been 211 subjected to forced disappearance an investigation should be opened ex officio, without delay, and in a serious, 212 impartial, and effective manner. In any case, every State authority, public or private officer who is aware of acts 213 purported to forcibly disappear persons, shall immediately report them. 204 I/A Court H.R., Case of García-Prieto et al.. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 20, 2007. Series C, No. 168. par. 101. 205 I/A Court H.R.., Case of Bulacio. Judgment of September 18, 2003. Series C, No. 100. par. 114; I/A Court H.R., Case of the Rochela Massacre. Judgment of May 11, 2007. Series C No. 163, par. 146; I/A Court H.R., Case of the Miguel CastroCastro Prison. Judgment of November 25, 2006. Series C, No. 160. par. 382. 206 I/A Court H.R., Case of Cantoral-Huamaní and García-Santa Cruz. Preliminary Objections, Merits, Reparations and Costs. Judgment of July 10, 2007. Series C, No. 167. par. 130; I/A Court H.R., Case of the Massacre of Pueblo Bello. Judgment of January 31, 2006. Series C, No. 140. par. 120; and I/A Court H.R., Case of Huilca Tecse. Judgment of March 3, 2005. Series C, No. 121, par. 66. 207 I/A Court H.R., Case of Zambrano-Vélez et al. Merits, Reparations and Costs. Judgment of July 4, 2007. Series C, No. 166. par. 122. 208 I/A Court H.R., Velásquez Rodríguez Case. Judgment of July 29, 1988. Series C, No. 4. par. 177; I/A Court H.R., Case of Cantoral-Huamaní and García-Santa Cruz. Preliminary Objections, Merits, Reparations and Costs. Judgment of July 10, 2007. Series C, No. 167. par. 131; and I/A Court H.R., Case of Zambrano-Vélez et al. Merits, Reparations and Costs. Judgment of July 4, 2007. Series C, No. 166. par. 120. 209 I/A Court H.R., Velásquez Rodríguez Case. Judgment of July 29, 1988. Series C, No. 4. par. 177; I/A Court H.R., Case of Zambrano-Vélez et al. Merits, Reparations and Costs. Judgment of July 4, 2007. Series C, No. 166. par. 120. 210 I/A Court H.R., Case of Goiburú et al. Judgment on Merits, Reparations and Costs Judgment of September 22, 2006. Series C, No. 153. par. 84; Case of Anzualdo Castro v. Peru, Judgment of September 22, 2009, Series C No. 202, par. 59; and Case of Radilla Pacheco v. Mexico. Preliminary Objections, Merits, Reparations and Costs Judgment of November 23, 2009. Series C, No. 209, par. 139. 211 Case of Radilla Pacheco v. Mexico. Preliminary Objections, Merits, Reparations and Costs Judgment of November 23, 2009. Series C, No. 209. par. 143. 212 Case of Anzualdo Castro v. Peru, Judgment of September 22, 2009, Series C No. 202, par. 65, and Case of Radilla Pacheco v. Mexico, Preliminary Objections, Merits, Reparations and Costs. Judgment of November 23, 2009. Series C, No. 209, par. 143. 213 Case of Anzualdo Castro v. Peru, Judgment of September 22, 2009, Series C No. 202, par. 65, and Case of Radilla Pacheco v. Mexico, Preliminary Objections, Merits, Reparations and Costs. Judgment of November 23, 2009. Series C, No. 209, par. 143.