- 74 - B. FULL INVESTIGATION, IDENTIFICATION, PROSECUTION AND EVENTUAL PUNISHMENT OF ALL THE MASTERMINDS AND PERPETRATORS 214. The Court has established that the State did not comply with its obligation to investigate fully and effectively the human rights violations that occurred in the instant case. The Court finds that the ineffectualness of the proceedings was clearly revealed when analyzing the lack of due diligence in the way in which the official investigation measures were undertaken, by the absence of a vision of the extrajudicial execution as a complex crime owing to the participation of different State agents and members of paramilitary groups. Furthermore, the lack of due diligence is also revealed by the failure to investigate the threats in the above-mentioned context and by the alleged existence of an extermination plan. Owing to the absence of an investigation with these characteristics, as well as other obstacles de facto, the Senator’s execution remains in impunity. 215. Additionally, the Court emphasizes that, as has been proved, given the complex method of execution of the crime in this case, the absence of an exhaustive investigation has been one of the factors that have impeded the identification, prosecution and, when applicable, punishment of all those responsible (supra paras. 124, 125 and 167). This situation has led to the impunity of the serious human rights violations committed jointly by members of paramilitary groups and agents of the armed forces. 216. Based on the foregoing, the State must use all necessary means, pursuant to its domestic laws, to continue conducting the investigations that are underway effectively and with the greatest diligence, and initiate any that may be necessary in order to individualize, prosecute and eventually punish all those responsible for the extrajudicial execution of Senator Manuel Cepeda Vargas, and to remove all the material and legal obstacles, that maintain impunity in this case. In particular, the State must conduct the investigations based on the following criteria:313 (a) Investigate effectively all the facts and background of this case, including the alleged existed of the “coup de grâce plan” or other plans designed to intimidate and murder members of the UP, such as the corresponding investigations underway by the office of the Prosecutor General of the Nation and, to this end, it must adopt all necessary measures to detect and reveal patterns of systematic violence against the collectivity to which Mr. Cepeda belonged; (b) Identify the group of individuals involved in the planning and execution of the facts, including those who designed, planned or assumed control, decision or leadership of their implementation, and those who performed the necessary logistic functions to execute the decisions taken, even if senior civil authorities, high-ranking military officers or intelligence services are involved, avoiding omissions in following up on logical lines of investigation; (c) To this end, establish coordination mechanisms between the different State organs and institutions with powers to investigate, and other existing or future entities in order to conduct the most coherent and effective investigations, so that the protection of the human rights of the victims is one of the objectives of the proceedings, particularly in cases of serious violations. 313 Cf. Case of the Dos Erres Massacre v. Guatemala, supra note 57, para. 233.