90 145. The second phase of the military intelligence operation consisted of keeping watch on, following, and extra-legally executing the victims. This was done by a group of specialists of the Presidential General Staff (supra paras. 134.3, 134.4, 134.6, 134.10 and 134.11). The execution of Myrna Mack Chang was not an isolated act carried out by the Presidential General Staff specialist Noel de Jesús Beteta Alvarez, but rather the result of a careful operation developed by the high command of that body, directly executed by Sergeant Beteta Alvarez (supra paras. 134.5 and 134.22). In this regard, Noel de Jesús Beteta Alvarez stated, with respect to the modus operandi of the Presidential General Staff, that: [t]his type of murder missions is not often, it depends on the situation, but at that time there was a lot of work. I think that there were perhaps some thirty murder missions, only for me. This is aside from the rest of the group, so the amount is twenty by thirty. Some six hundred a year only in that office (the EMP). In Myrna’s case they passed me the file, I analyzed it and began the surveillance. This type of missions last no more than fifteen days from when we single the person out until the time of the execution. We do not report until the mission has been completed. Once that mission was completed, I shredded the file, I burned it, and I did not speak about the matter any more to anyone at the office. All my reports to Juan Valencia Osorio, my supervisor, were verbal. It included the way to eliminate her so that people thought it was a common crime. Then they tried to eliminate me physically and armed people even kept watch on the house and came asking for me. I am sure that Juan Valencia Osorio ordered that I be killed. That is why I left the country. Once I was a prisoner they did not talk to me nor send me any messages. When my mother said that they were coming to the house I understood the message.237 146. In this regard, the CEH Report pointed out that: [m]ost of the human rights violations took place with knowledge by or under orders from the highest authorities of the State. Evidence from various sources (statements of former members of the Armed Forces, declassified documentation, data from various organizations, testimony of Guatemalan eminent persons) all points to the fact that the intelligence services of the Army, especially the G-2 and the Presidential General Staff, obtained information on all types of individuals and civil organizations, evaluated their behavior in their respective spheres of activity, prepared lists of those to be repressed due to their allegedly subversive nature, and then, according to each case, captured, interrogated and tortured them, made them disappear, or executed them. […T]he responsibilities for many of these violations include, in the line of military command and in that of political and administrative responsibility, the highest levels of the Army and of successive Governments. […T]he excuse that the lower-ranking officers acted with a great deal of autonomy and decentralization, which would explain “excesses” and “mistakes” that were not ordered by the commanding officers, is a groundless argument according to the investigation conducted by the CEH. The notorious fact that no commander, officer or intermediate authority in the Army or the security forces of the State has been prosecuted or convicted for his acts in violation of human rights over so many years strengthens the evidence that most said violations resulted from an institutional policy that ensured an impenetrable impunity, which continued throughout the period investigated by the CEH.238 147. The REMHI Report, in turn, in fitting with the statements by Noel de Jesús Beteta Alvarez regarding the modus operandi, in connection with the extra-legal executions in Guatemala, found that: 237 Cf. Report by the Proyecto Interdiocesano de Recuperación de la Memoria Histórica, “Guatemala: Nunca Más: los mecanismos del horror,” volume II, page 190; and transcripts of interviews with Noel de Jesús Beteta Alvarez (file with annexes to the application, annex 52.2, leaves 1152 to 1259). 238 Cf. report by the Comisión para el Esclarecimiento Histórico, “Guatemala, memoria del silencio” in June, 1999, Conclusions, pages 47 to 48.