obligations relating to the use of force by the State. 73 Taking the foregoing into account, the Court has established that, in order to ensure the appropriate measures if the use of force becomes essential, this must be used in keeping with the principles of legality, absolute necessity, and proportionality.74 The assessment of the conventionality of the use of force should be made in relation to the context and all the circumstances of the events, 75 taking the foregoing criteria into account. In the instant case, this Court must determine whether the actions of the State agents conformed to the American Convention in relation to the deprivation of life of Robert Ignacio Díaz Loreto, David Octavio Díaz Loreto and Octavio Ignacio Díaz Álvarez, which occurred at the hands of CSOPEA officials. To this end, it will assess the evidence presented by the parties and by the Commission in order to determine whether the use of force by the CSOPEA was lawful and legitimate and, if applicable, necessary and strictly proportionate. 64. As indicated in the chapter on the facts (supra para. 28), there are two versions of the circumstances surrounding the deaths of Robert Ignacio Díaz Loreto, David Octavio Díaz Loreto and Octavio Ignacio Díaz Álvarez. According to one of these versions, it is affirmed that, on January 6, 2003, several CSOPEA officers burst into the home of the Díaz Loreto family, obliged Robert Ignacio Díaz Loreto to exit the house and shot him without any reason. In addition, they shot him again when placing him in the patrol vehicle and delayed going to the health center where he could have been cared for in time (supra para. 39). Subsequently, Octavio Díaz and David Díaz, respectively Robert’s father and brother, got into a car to search for Robert and, on the way, they were allegedly intercepted by a police detail that obliged them to stop. When they descended from the car, the police allegedly shot David Octavio Díaz Loreto and Octavio Ignacio Díaz Álvarez, and took them to the hospital where they were pronounced dead on arrival. This version is revealed by several statements by witnesses and members of the alleged victims’ family as well as by the autopsy performed on the corpse of Robert Ignacio Díaz Loreto (supra para. 43). 65. Meanwhile, a second version asserts that between 6 and 6.30 p.m. a police operation was conducted in response to a report of a robbery by R.D.P., that same day; that when the police reached the scene of the incident, and the person who had reported the robbery having identified the presumed authors of the offense, the police officers had proceeded to order those present not to move. In response the presumed offenders had fired on the officers and the latter had responded resulting in an exchange of gunfire. As a result, “two of the men were able to escape by nearby streets,” while Robert Ignacio Díaz Loreto fell to the ground seriously wounded; therefore, it had been necessary to take him to the nearest health facility. Cf. Case of Montero Aranguren et al. (Retén de Catia) v. Venezuela. Preliminary objection, merits, reparations and costs. Judgment of July 5, 2006. Series C No. 150, paras. 68 and 69, and Case of Women Victims of Sexual Torture in Atenco v. Mexico, para. 160. 73 These consist in: (a) Legality. The exceptional use of force must be established by law and a regulatory framework for its use must exist; (b) Legitimate purpose. The use of force must be addressed at achieving a legitimate purpose that is not contrary to the American Convention; (c) Necessity. The use of force must be limited to the inexistence or unavailability of other measures to protect the life and integrity of the person or situation that it is sought to protect, in keeping with the circumstances of the case, and (d) Proportionality: The measures and method used must be in keeping with the level of resistance offered and the danger that exists. Thus, agents must apply the criteria of differentiated and progressive use of force, determining the degree of cooperation, resistance or violence of the subject against whom the intervention is intended and, on this basis, employ negotiating tactics, control or use of force, as required. Cf. Case of Nadege Dorzema et al. v. Dominican Republic. Merits, reparations and costs. Judgment of October 24, 2012. Series C No. 251, para. 85, and Women Victims of Sexual Torture in Atenco v. Mexico, para. 162. See also, Basic Principles on the Use of Force, Principles Nos. 1, 4, 5, 7, 8, 9 and 11. 74 Cf. Case of Montero Aranguren et al. (Retén de Catia) v. Venezuela, para. 82, and Case of Cruz Sánchez et al. v. Peru. Preliminary objections, merits, reparations and costs. Judgment of April 17, 2015. Series C No. 292, para. 266. 75 -21-