21 56. The Court has interpreted the above-cited Article in the Velásquez Rodríguez and Godínez Cruz Cases as follows: Article 1(1) is essential in determining whether a violation of the human rights recognized by the Convention can be imputed to a State Party. In effect, that article charges the States Parties with the fundamental duty to respect and guarantee the rights recognized in the Convention. Any impairment of those rights which can be attributed under the rules of international law to the action or omission of any public authority constitutes an act imputable to the State, which assumes responsibility in the terms provided by the Convention. (Velásquez Rodríguez, Judgment of July 29, 1988. Series C No. 4, para. 164; Godínez Cruz Case, Judgment of January 20, 1989. Series C No. 5, para. 173.) According to Article 1(1), any exercise of public power that violates the rights recognized by the Convention is illegal. Whenever a State organ, official or public entity violates one of those rights, this constitutes a failure of the duty to respect the rights and freedoms set forth in the Convention. (Ibid., para. 169 and para. 178, respectively.) Thus, in principle, any violation of rights recognized by the Convention carried out by an act of public authority or by persons who use their position of authority is imputable to the State. However, this does not define all the circumstances in which a State is obligated to prevent, investigate and punish human rights violations, nor all the cases in which the State might be found responsible for an infringement of those rights. An illegal act which violates human rights and which is initially not directly imputable to a State (for example, because it is the act of a private person or because the person responsible has not been identified) can lead to international responsibility of the State, not because of the act itself, but because of the lack of due diligence to prevent the violation or to respond to it as required by the Convention. (Ibid. para. 172 and paras. 181-182, respectively.) 57. In the instant case, Colombia has undertaken a prolonged judicial investigation, not free of defects, to find and sanction those responsible for the detention and disappearance of Isidro Caballero-Delgado and María del Carmen Santana, and those proceedings have not been closed. 58. As the Court held in the cases cited above, [i]n certain circumstances, it may be difficult to investigate acts that violate an individual's rights. The duty to investigate, like the duty to prevent, is not breached merely because the investigation does not produce a satisfactory result. (Velásquez Rodríguez Case, supra 56, para. 177; Godínez Cruz Case, supra 56, para. 188.) Nevertheless, to fully ensure the rights recognized in the Convention, it is not sufficient that the Government undertake an investigation and try to sanction those guilty; rather it is also necessary that all this Government activity culminate in the reparation of the injured party, which in this case has not occurred. 59. Therefore, as Colombia has not remedied the consequences of the violations carried out by its agents, it has failed to comply with the duties that the above-cited Article 1(1) of the Convention imposes on it.