33 167. The Court has written that in fulfillment of their duty to investigate a violation of the right to life with the necessary due diligence, States have an obligation to act with rigorous attention to detail from the very outset of the investigation.111 Here, the Inter-American Court has taken into consideration the United Nations Manual on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions, and wrote that: At a minimum, state authorities conducting an inquiry shall seek, inter alia: a) to identify the victim; b) to recover and preserve evidentiary material related to the death in order to aid in any potential prosecution of those responsible; c) to identify possible witnesses and obtain statements from them concerning the death; d) to determine the cause, manner, location and time of death, as well as any pattern or practice that may have brought about the death; and e) to distinguish between natural death, accidental death, suicide and homicide. The Court further notes that: a) the crime scene must be exhaustively investigated and b) autopsies, as well as analyses of skeletal remains, must be rigorously performed by competent professionals, 112 employing the most appropriate procedures. 168. The Court has also held that the authorities must take reasonable measures to preserve the evidence necessary to conduct the investigation.113 169. As for the importance of the conduct of the authorities in charge of the first steps in an investigation, the Court has held that the requisite due diligence and “independence and impartiality also extend to the non-judicial bodies responsible for the investigation prior to the judicial proceedings, conducted to determine the circumstances of a death and the existence of sufficient evidence. In the absence of these requirements, the State cannot subsequently exercise effectively and efficiently its authority to bring charges and the courts cannot conduct the judicial proceedings that this type of violation calls for.”114 170. As for the duration of the investigations, the Commission is reminded that one of the judicial guarantees that Article 8(1) of the Convention establishes is that courts are to decide cases within a reasonable time. 171. The Inter-American Court has held that a long delay may per se constitute a violation of the principle of due process.115 It is for the State to explain and prove why it has required more time 111 I/A Court H.R., Case of Zambrano Vélez et al. v. Ecuador. Merits, Reparations and Costs. Judgment of July 4, 2007. Series C No. 166, paragraph 121. 112 I/A Court H.R., Case of the Moiwana Community v. Suriname. Judgment of June 15, 2005. Series C No. 124, paragraph 149; I/A Court H.R., Case of the Miguel Castro Castro Prison v. Peru. Judgment of November 25, 2006. Series C No. 160, paragraph 383. Citing the United Nations Manual on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions, Doc. E/ST/CSDHA/.12 (1991). 113 I/A Court H.R., Case of Zambrano Vélez et al. v. Ecuador. Merits, Reparations and Costs. Judgment of July 4, 2007. Series C No. 166, paragraph 122. 114 I/A Court H.R., Case of Cantoral Huamaní and García Santa Cruz v. Peru. Preliminary Objection, Merits, Reparations and Costs. Judgment of July 10, 2007. Series C No. 167. Paragraph 133. 115 I/A Court H.R., Case of García Asto and Ramírez Rojas v. Peru. Judgment of November 25, 2005. Series C No. 137, paragraph 166; Case of Gómez Palomino v. Peru. Judgment of November 22, 2005. Series C No. 136, paragraph 85; Case of the Moiwana Community v. Suriname. Judgment of June 15, 2005. Series C No. 124, paragraph 160.