account the level of participation of all the State agents; (ii) the investigation must be given a certain degree of public scrutiny 326 owing to the possible public interest because of the rank of the agents presumed to be involved; (iii) prompt intervention at the scene of the incident and appropriate handling of the scene of the crime, as well as preserving this in order to protect all the evidence, 327 as well as ballistic tests when firearms have been used, 328 especially by State agents; (iv) determination of whether the body has been touched or moved 329 and of the sequence of events that could have led to the death, 330 as well as a preliminary examination of the corpse to protect any evidence that could be lost in its manipulation and transport, 331 and (v) performance of an autopsy by trained professionals that reveals any evidence indicating presumed acts of torture 332 by State agents B.3.2 The initial investigation procedures 255. The Court observes that, on December 31, 1996, after the events had occurred, a summary investigation was opened by the Technical Unit of the Judicial Police, Mariño Division (supra para. 97) who went to the scene of the crime. A team from the Forensic Medicine Unit and the Ninth Prosecutor also went to the crime scene (supra para. 97). In the context of this summary investigation initial procedures were carried out to collect evidential material; these included, in particular: (a) removal of the corpse and its transfer to the Forensic Medicine Unit (supra para. 98); (b) visual inspection of the area where the incident occurred at 11 a.m. on December 31, 1996, during which 17 photographs were taken, and seven empty cartridges and a piece of cotton with a reddish-brown substance were collected (supra para. 98); (c) two inspections of the corpse on December 31, 1996 (supra para. 98); (d) autopsy of the corpse performed the same day, during which three bullets were recovered (the autopsy was expanded subsequently (supra para. 98); (e) reception of the statements of the police agents who were transferring Eduardo Landaeta (supra paras. 216 and 217); (f) tests for gunpowder residue on the hands of two police agents (supra para. 99); (g) topographic survey and ballistics trajectory on August 14, 1997, which were subsequently expanded (infra para. 259); (h) appraisal and valuation of the vehicle that transported Eduardo Landaeta of January 1997; 333 (i) appraisal using chemical reagents to search for fingerprints (experticia de “activación especial”) on the vehicle that transported Eduardo Landaeta of March 1997, 334 which was carried out again in 2004, and (j) other procedures. 335 325 Case of Velásquez Rodríguez. Merits, supra, para. 177, and Case of Veliz Franco et al., supra, para.183. 326 Cf. Istanbul Protocol, supra, para. 78(a), and ICRC, Guidelines for Investigating Deaths in Custody, supra, p. 13. 327 Cf. CICR, Guidelines for Investigating Deaths in Custody, supra, p. 13, Case of Myrna Mack Chang, supra, para. 166, and Case of Veliz Franco et al., supra, para. 191. 328 CICR, Guidelines for Investigating Deaths in Custody, supra, pp. 13, 15 to 17, Case of Garibaldi, supra, para. 125, and Case of Nadege Dorzema et al., supra, para. 192. 329 Cf. ICRC, Guidelines for Investigating Deaths in Custody, supra, p. 18, Case of González et al. (“Cotton Field”), supra, para. 310, and Case of Veliz Franco et al., para. 192. 330 Cf. ICRC, Guidelines for Investigating Deaths in Custody, supra, pp. 18 and 19. 331 Cf. ICRC, Guidelines for Investigating Deaths in Custody, supra, pp. 33 a 36. 332 Cf. Vargas Areco v. Paraguay. Merits, reparations and costs. Judgment of September 26, 2006. Series C No. 155, para. 87, and ICRC, Guidelines for Investigating Deaths in Custody, supra, pp. 13 and 18 to 20. Also, under the Istanbul Protocol, investigation of a case of torture requires a general assessment of all the injuries and not the correlation of each of them with a particular form of torture. Cf. Istanbul Protocol, supra, para. 188. 333 Cf. Appraisal and valuation of a vehicle of January 5, 1997 (annexes to the answering brief of the State, folio 7171). 334 Cf. Appraisal using chemical reagents to search for fingerprints on vehicle of March 10, 1997 (annexes to the answering brief of the State, folios 7192 and 7193). 335 For example, the reception of testimony from the police agents who took part in the transfer, and also from the parents of Eduardo Landaeta and two eyewitnesses; forensic and hematological testing of Eduardo 70