key and conditioning element to protect certain rights perceived as affected or breached by these situations, such as the right to life.167 133. Likewise, the Inter-American Court has pointed out that the duty to investigate must be reinforced where there are clues that state agents have been involved. 168 About this matter, the European Court of Human Rights indicated that: the obligation to protect the right to life .[...] requires by implication that there should be some form of effective official investigation when individuals have been killed as a result of the use of force. These investigations must be conducted […] without considering if the perpetrators are agents of the State or third parties. Nevertheless, when the involvement of agents or bodies of the State is alleged, specific requirements can be applied on the effectiveness of the investigation. (…) The essential purpose of such investigation is to secure the effective implementation of the domestic laws which protect the right to life and, in those cases involving State agents or bodies, to ensure their accountability for deaths occurring under their responsibility.169 134. On the basis of the above, in the present case the duty to investigate must be fulfilled with special diligence and seriousness, because of the existence of clues of a direct participation or complicity or collaboration of state agents in Ángel Pacheco's death. 135. The Commission reiterates that, in view of clues of this nature, which would entail a direct attribution of the State's international responsibility, it would pertain to the authorities in charge of the investigation to make all necessary efforts to clarify the possible responsibilities or ties of state authorities in a violation of the right to life. 170 Thus, it behooves the State to conduct a meticulous, serious, and diligent investigation to find out the truth or disprove the clues indicating participation of state agents. 136. With respect to this duty, the Court has pointed out that, in cases of violent deaths, where there are clues of the participation of state agents, the State must adopt all necessary measures to determine the corresponding individual responsibilities. 171 The Court found that, in those cases where this does not happen: (…) it is reasonable to assess as evidence the indication contained in the case file that point to the involvement of state agents in these events, particularly those handled by the very state agencies that were in charge of the investigation which have not been disproven by the State. Reaching any other conclusion would entail allowing the State to resort to its own negligence or inefficacy for the criminal investigation to release itself from responsibility for the violation of Article 4(1) of the Convention.172 137. Likewise, the Court has repeated that the failure to investigate alleged violations against a person where there are clues of participation by state agents, "prevents the State from presenting a satisfactory and convincing explanation of the [facts] alleged and from disproving allegations about its 167 I/A Court H.R., Case of the Pueblo Bello Massacre v. Colombia. Judgment of January 31, 2006. Series C No. 140, para. 145. 168 I/A Court H.R., Case of Castillo-González et al. v. Venezuela. Merits. Judgment of November 27, 2012. Series C No. 256, para. 127. 169 ECHR. Khaindrava and Dzamashvili v. Georgia, Judgment of September 8, 2010, para. 58: McCann and Others v. the United Kingdom. Judgment of September 27, 1995, paras. 49 and 161; and Mastromatteo v. Italy. Judgment of October 24, 2002, para. 89. 170 IACHR, Report No. 120/10, Case 12.605, Merits, Joe Luis Castillo González, Venezuela, October 22, 2010, para. 109. I/A Court H.R., Case of Kawas-Fernández v. Honduras. Merits, Reparations and Costs. Judgment of April 3, 2009. Series C No. 196, para. 97. 171 172 I/A Court H.R., Case of Kawas-Fernández v. Honduras. Merits, Reparations and Costs. Judgment of April 3, 2009. Series C No. 196, para. 97.