7 human remains be performed by competent professionals, using the best available procedures.20 25. That the investigators of reports or indications of extra-judicial executions must be independent individuals. Such independence should be, not only institutional or hierarchical, but also actual from any institution or person that may be subject to investigation.21 26. That as regards to the effective investigation and documentation of torture and cruel, inhuman and degrading treatment, the Court has held that the principles of independence, impartiality, competence, diligence and promptness should apply to any legal system and govern the investigation of any alleged acts of torture.22 27. That at the time of hearing report or indications of acts of torture, competent authorities will be entitled to access any information deemed necessary for the actual performance of the investigation, and will indeed be obliged to exercise that power. To that effect, the necessary technical and budgetary resources should be available, including the power to bound the officers allegedly involved in the crime investigated to appear and give their testimony.23 28. That the investigators of acts of torture and mistreatment must gather all possible material evidence. The aim is at successfully preserving evidence so that it can be used in a potential criminal proceeding. To that effect, it is necessary for the investigators to have access to the places where acts of torture were allegedly committed.24 29. That any places subject to investigation as alleged crime scenes must be closed so that no potential evidence is lost and only investigators and their staff will be allowed access thereto. All evidence will be gathered, handled, packed and identified in a proper manner, and must be kept at a place to safeguard it from contamination, touching or loss.25 30. That in the instant case, the Court established in its Judgment on the merits that: 229. In the file there are many records which reveal that the judicial authorities who conducted the proceedings deriving from the abduction, torture and homicide of Henry Giovanni Contreras, Julio Roberto Caal Sandoval, Jovito Josué Juárez Cifuentes and Federico Clemente Figueroa Túnchez, and the homicide of Anstraum Aman Villagrán Morales, failed in their duty to encourage an adequate investigation and judicial proceeding that would lead to the punishment of those responsible, and affected the right of the victims’ next of kin to be heard and to have their accusations discussed by an independent and impartial tribunal. 230. In this respect, the Court observes that the domestic judicial proceedings revealed two types of serious defect: first, investigation of the crimes of abduction and torture was completely omitted 20 Cf. Case of Juan Humberto Sánchez, supra note 19, para. 127 and 132; Case of the Miguel Castro-Castro Prison v. Perú, supra note 7, para. 383; and Case of Zambrano-Vélez et al. v. Ecuador, supra note 19, para. 121. 21 Cf. Case of Montero-Aranguren et al. (Detention Center of Catia) v. Venezuela, supra note 16, para. 81; and Case of Zambrano-Vélez et al. v. Ecuador, supra note 19, para. 122. 22 Cf. Case of Bueno Alves v. Argentina, supra note 7, para. 108; and Case of Bayarri v. Argentina, supra note 11, para. 92. 23 Cf. Istanbul Protocol (Manual on the Effective Investigation and Documentation of Torture and Other Cruel, Inhuman and Degrading Treatment or Punishment), Office of the High Commissioner of the United Nations for Human Rights (OHCHR). Series on Professional Training No. 8, Newsletter 1, United Nations, New York and Genève, 2004, principles contained in para. 79. 24 Cf. Istanbul Protocol, supra note 23, para. 101. 25 Cf. Istanbul Protocol, supra note 23, para. 102.