142. Moreover, the Commission notes that as established in this document, due diligence in the legal and medical investigation of a death requires maintaining the chain of custody of each item of forensic evidence.244 In this regard, the Inter-American Court has stated that: This entails keeping a precise written record, complemented, as applicable, by photographs and other graphic elements, to document the history of the item of evidence as it passes through the hands of the different investigators responsible for the case.245 143. First of all, nothing in the record indicates that any formalities were conducted at the scene of the crime on the day it occurred. On the contrary, the IACHR notes that there was an unjustified delay in carrying out the judicial inspection of the crime scene in this case. That inspection was effected almost one month after Carlos Escaleras’s murder. The effects of the delay were recognized by the trial judge himself, who stated that no kind of evidence could be gathered other than the spent cartridges already collected by the prosecution service (see para. 80 above). 144. Second, the IACHR notes that nothing in the record indicates that the scene of the crime was protected following the incident or that any steps were taken to preserve the evidence. Other than the reference to the cartridges, there are no documentary or photographic records of Mr. Escaleras’s death or of any other evidence gathered at the crime scene. The Commission therefore notes that from the very onset, one of the minimum components cited above – namely, an exhaustive evaluation of the scene of the crime – was omitted. 145. Third, the Commission also notes that there is no record of the autopsy performed on Mr. Escaleras Mejía’s body. On the contrary, as indicated in the section setting out the proven facts, on May 27, 1999, the prosecution service acknowledged that the report of the examination of Carlos Escaleras’s body was not available (see para. 86 above). Fourth, the IACHR notes that according to the available information, no reconstruction of the incident was carried out. Finally, the Commission observes that during the first months following Mr. Escaleras’s death, the investigation focused exclusively on the Iraheta Pineda brothers. The IACHR finds no evidence in the judicial case file to link them to the murder of Carlos Escaleras and that the ballistic examination of their weapons was conducted almost two months after the facts of the case. 146. Based on these elements, the IACHR finds that following Mr. Escaleras Mejías’s homicide, the police, prosecutors, and judicial authorities failed to pursue the minimum formalities in accordance with the standards set by the Commission and the Court in numerous cases, in line with the “Manual on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions.” Therefore, from the very onset, the investigation suffered from serious limitations that, as will be examined in the following sections, had a direct impact on the situation of partial impunity that characterizes the facts of this case. 1.2.2. Subsequent formalities 147. In its examination of the subsequent formalities carried out, the Commission has identified various shortcomings, irregularities, and omissions throughout the investigation, which contributed to the convictions of one perpetrator (Lucas García Alfaro) and one accomplice (Leodán Machado) being handed down 5 and 13 years after the facts, the failure to clarify the motivation behind the crime, and the continued impunity enjoyed to date by those who masterminded it. a. Absence of logical and timely lines of investigation regarding the possible direct participation of state agents 244 Manual on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions; and I/A Court H. R., Case of González et al. (“Cotton Field”) v. Mexico, Preliminary Objection, Merits, Reparations, and Costs, Judgment of November 16, 2009, Series C No. 205, para. 305. 245 I/A Court H. R., Case of González et al. (“Cotton Field”) v. Mexico, Preliminary Objection, Merits, Reparations, and Costs, Judgment of November 16, 2009, Series C No. 205, para. 305. 29