35 of the said guarantees inherent to the opening of a proceeding cannot be established[; …] the State […] acknowledges the breach of the right to truth, [which is] an emerging principle underlying Articles 8 and 25 of the Convention respectively”. 119. As indicated in the previous chapters (supra paras. 67, 94, 88-90, 109 and 110), upon learning that three persons had been deprived of their life as a consequence of the lethal use of force by state agents, by means of firearms and in an operation of such nature, the State should have activated, ex officio and without delay, mechanisms to carry out an appropriate control and verification of the legality of the use of force, through a serious, independent, impartial and effective investigation of the fact at the domestic level. 120. The Court has established that the obligation to investigate is not to be undertaken by the State as a mere formality condemned beforehand to be unsuccessful99, or as a mere reaction to private interests, which would depend on the procedural initiative of the victims or their family members or on the submission of evidentiary elements by private individuals100. This is not contrary to the right of the victims of human rights violations or their family members to be heard during the investigation and the judicial proceedings, as well as to their right to participate extensively in them101. 121. This Court has specified that the effective determination of the truth within the framework of the obligation to investigate the death of a person must be showed in the first stages of the proceeding, with all diligence. In this regard, on the grounds of the United Nations Manual on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions, this Court has defined the guiding principles that should be observed when it is considered that a death may be due to extrajudicial execution. The State authorities that conduct an investigation must, inter alia, (a) identify the victim; (b) recover and preserve the probative material related to the death, in order to facilitate any investigation; (c) identify possible witnesses and obtain their statements in relation to the death under investigation; (d) determine the cause, method, place and moment of the death, as well as any pattern or practice that could have caused the death, and (e) distinguish between natural death, accidental death, suicide and murder. In addition, it is essential to search exhaustively the scene of the crime and autopsies and analyses of human remains must be carried out rigorously by competent professionals, using the most appropriate procedures102. 122. Moreover, in such cases, it is particularly important that the competent authorities adopt all reasonable measures to guarantee the necessary probative material in order to carry out the investigation103 and that they be independent, both de jure and de facto, from the officials involved Cf. Case of Velásquez Rodríguez, supra note 75, para. 177. See also Case of the Miguel Castro-Castro Prison, supra note 14, para. 255; Case of Ximenes Lopes, supra note 60, para. 148. 99 Cf. Case of Velásquez Rodríguez, supra note 75, para. 177. See also Case of the Miguel Castro-Castro Prison, supra note 14, para. 255, and Case of Goiburú et al., supra note 75, para. 117. 100 Cf. Case of the “Street Children” (Villagrán-Morales et al.), supra note 59, para. 227. See also Case of Miguel Castro-Castro Prison, supra note 14, para. 255, and Case of Goiburú et al., supra note 75, para. 117. 101 Cf. Case of the Moiwana Community. Judgment of June 15, 2005. Series C No. 124, para. 149. See also Case of the Miguel Castro-Castro Prison, supra note 14, para. 383, and Case of Vargas Areco, supra note 64, para. 91. Similarly, see also the United Nations Handbook for the Effective Prevention and Investigation of Extra-legal, Summary and Arbitrary Executions, Doc. E/ST/CSDHA/.12 (1991). 102 103 Cf. Case of Montero Aranguren et al. (Detention center of Catia), supra note 31, para. 81. Similarly, see also Erdogan and Others v. Turkey, supra note 66, para. 89; ECHR, Kakoulli v. Turkey, supra note 66, para. 123, and ECHR, Hugh Jordan v. the United Kingdom, 4 May 2001, no. 24746/94, paras. 107-108.