21 this case, the victim’s relatives have moved the proceeding forward by gathering evidence on the facts, carrying out interviews, and bringing witnesses forward for the case, all without results. 115. The investigations moved forward by the State’s judicial branch showed indications of manipulation of evidence gathering, obstruction of justice and procedural delay, as well as a lack of due 75 diligence in the investigation. Thus for example, there have been accusations that the witnesses were threatened - and some of them tortured - by agents of the State so that in the oral hearing they would reject their earlier testimony in which they clearly identified two federal police officers as the perpetrators of the execution of Jorge Omar Gutiérrez. The State has not challenged these facts and neither has it 76 submitted information on any inquiries it might have made into the acts of torture that were denounced. 116. In this sense, the IACHR notes that in its final report, the Special Investigative Commission warned about irregularities that had been introduced into the criminal case. It therefore requested that the Supreme Court consider reopening the case. These deficiencies blocked the possibility that the process proceed in keeping with the principles of due diligence. A poor or incomplete investigation of the facts makes it difficult to establish responsibility and can lead to impunity. The Commission has not received significant information from the State on the leads that, following the dismissal of the two individuals identified by witnesses as material perpetrators of the death of Jorge Omar Gutiérrez, are being followed. It notes that as of right now, no individual has been punished, generating impunity. 117. According to the evidentiary elements recorded in the case file before the IACHR, the investigations carried out into the murder of Jorge Omar Gutiérrez have been characterized by negligence of judicial authorities in the gathering of the evidence, the misrouting of the proceeding, and especially in the delay in its conclusion and consequent trial of the alleged perpetrators and masterminds. 118. Regarding procedural guarantees, the Court has established that “for true guarantees of fair trial to exist in a proceeding, pursuant to the provisions of Article 8 of the Convention, it is necessary to observe all the requirements that are designed to protect, to ensure or to assert the entitlement to a 77 right or the exercise thereof.” 119. In effect, the bodies of the inter-American system have understood that the duty to investigate with due diligence includes the obligation to carry out all necessary actions within a 78 reasonable period of time. Likewise, three basic standards have been established for determining 75 Annex 36. In a communication received on February 15, 2002, the petitioners alleged the following: Even when the judicial and police authorities had sufficient information to identify the alleged co-perpetrator of the murder of Jorge Omar Gutiérrez, who had been identified by witnesses as “Colorado” and who it was later learned was Officer Mostajo, and even when they had information allowing them to know his whereabouts, no results were achieved in that regard. Adolfo Ricardo Salvador, brother of Santillán’s former mistress, provided concrete information, the physical description and nickname... no progress was made in the parallel investigation that had been started into the threats, injuries and other crimes committed by police personnel to the detriment of witnesses in the case. The testimony given before the Special Commission by the mother of Santillán’s mistress, Claudia Acuña, indicating that she had been coerced into testifying in his favor during the oral trial had not been ratified in court because the case opened ex-officio had “disappeared.” Effectively, case No. 13.451, “Santillán, Carlos Mario, s/threats” had begun before the National Criminal and Preliminary Investigation Court No. 33. However, this court had declared that it did not have jurisdiction, and afterwards no progress was made. 76 With regard to the cover-up, it is worth noting the testimony submitted on October 4, 2000, by Officer Juan Eduardo Dávalos before the the Transitional Court No. 2 of the City of La Plata Judicial District. In the testimony, he stated that on chatting with Deputy Officer Segovia, who had established that he had brought Deputy Commissioner Gutiérrez to the train station, the Deputy Officer told him that he had not mentioned that another officer with the surname Chaves also accompanied him that night on patrol. He said he had not mentioned it “because otherwise it would complicate things.” In his testimony, Officer Dávalos said he would be willing to confront Officer Segovia. Annex 37. Testimony of Juan Eduardo Dávalos dated October 4, 2000, and given before the the Transitional Court No. 2 of the City of La Plata Judicial District. Annexes submitted by the petitioners in communication dated September 26, 2001. 77 Inter-American Court, Case of Juan Humberto Sánchez. Judgment of June 7, 2003. Series C No. 99, para. 124. 78 Inter-American Court, Case of the Serrano Cruz Brothers. Judgment of March 01, 2005. Series C No. 120. para. 65.