130 responsible.254 217. The Court has established, regarding the principle of reasonable term set forth in Article 8(1) of the American Convention, that it is necessary to take into account three aspects to decide whether the time taken by a proceeding is reasonable: a) complexity of the matter, b) procedural activity of the interested party, and c) conduct of the judicial authorities.255 218. Nevertheless, the Court deems that pertinence of those three criteria to decide whether the term of a proceeding is reasonable depends on the circumstances of each case. 219. In point of fact, it is necessary to recall that the instant case is one in which there were extralegal executions, and in this type of cases the State has the duty to ex officio and promptly begin a serious, impartial and effective investigation.256 During the investigative and judicial processes, the victims of human rights violations, or their next of kin, must have ample opportunity to participate and be heard, both regarding elucidation of the facts and punishment of those responsible, and in seeking fair compensation.257 However, the State is responsible for effectively seeking to establish the truth, and this depends neither on the procedural initiative of the victims or of their next of kin, nor on their contributing evidence.258 In this case, some of the accused have been tried and convicted in absentia. Furthermore, limited participation of the next of kin in the criminal proceedings, whether as civil parties or as witnesses, is a consequence of the threats suffered during and after the massacre, of their situation of displacement and of fear of participating in said proceedings. Therefore, it can hardly be argued that in a case such as this one the procedural activity of the interested party should be considered a decisive criterion to decide whether the term has been reasonable. 220. Regarding the complexity of the case, the Court recognizes that the matter investigated by the domestic judicial bodies is a complex one. Despite that complexity, to date there are concrete outcomes of the investigation and the criminal proceeding that, while they are insufficient, have led to the conviction of several members of the Army, as well as of several members of paramilitary groups, for their participation in the facts (supra para. 96.126 e infra para. 230). 221. The massacre did in fact take place in the context of the domestic armed conflict in Colombia; there were a large number of victims –who were executed or displaced- and it took place in a remote region where access is difficult, among other 254 See Case of the Serrano Cruz Sisters, supra note 11, para. 66; Case of the 19 Tradesmen, supra note 190, para. 188, and Case of Myrna Mack Chang, supra note 5, para. 209. 255 See Case of the Moiwana Community, supra note 4, para. 160; Case of the Serrano Cruz Sisters, supra note 5, para. 67, and Case of Tibi, supra note 16, para. 175. Likewise see European Court of Human Rights. Wimmer v. Germany, no. 60534/00, § 23, 24 May 2005; Panchenko v. Russia, no. 45100/98, § 129, 8 February 2005, and Todorov v. Bulgaria, no. 39832/98, § 45, 18 January 2005. 256 See Case of the Moiwana Community, supra note 4, para. 145; Case of the Gómez Paquiyauri Brothers, supra note 185, para. 131, and Case of Myrna Mack Chang, supra note 5, para. 157. 257 See Case of the Moiwana Community, supra note 4, para. 147; Case of the Serrano Cruz Sisters. Judgment of March 1, 2005. Series C No. 120, para. 63, and Case of the 19 Tradesmen supra note 193, para. 186. 258 See Case of the Moiwana Community, supra note 4, para. 146; Case of the Serrano Cruz Sisters. supra note , para. 61, and Case of the 19 Tradesmen, supra note 193, para. 112.