127. This obligation to investigate is based on the facts previously analyzed (supra paras. 111 to 125). Indeed, regarding the alleged pulling of the victims’ testicles, in their statements in the domestic criminal proceeding, both Mr. Cabrera García and Mr. Montiel Flores indicated that soldiers had pulled their testicles while they were detained on the banks of Pizotla River. 177 On this point, the Court notes that although the medical certificates issued by the Mexican authorities regarding the victims’ physical integrity mentioned an injury to their testicles as a result of the arrest (supra paras. 114 to 120), the expert opinion of Dr. Tramsen and Dr. Tidball-Binz concluded, in relation to Mr. Cabrera, that “[t]he right testicle is retracted and reduced to half the size of the left testicle,” 178 while, in the case of Mr. Montiel, it indicated that his testicles were in normal condition. 179 Furthermore, it should be emphasized that the conclusions of the expert opinion of Dr. Tramsen and Dr. Tidball-Binz significantly coincide with those contained in the examination issued upon the release of Messrs. Cabrera and Montiel (supra para. 117) and with the expert opinion presented by expert witness Quiroga, 180 since the latter mentioned that “[t]he medical examination shows a retraction of the right testicle which was previously described in the physical examination by Physicians for Human Rights in July 2000.” 181 Nevertheless, the expert witness Gutierrez Hernández associated these last conclusions with degenerative problems characteristic of the victims’ age and cholesterol related problems. 182 128. At the same time, the Court notes that during the domestic criminal proceeding only Mr. Montiel mentioned that “they soaked him to give him [electric] shocks during short periods of time.” 183 Despite the foregoing, the representatives stated that Mr. Cabrera García received electric shocks in the left thigh. In this respect, the Court emphasizes that electric shocks are a form of torture different from others because it is difficult to determine if it was applied, since it is possible to use mechanisms to leave no visible marks. 184 The medical examination 177 In his affidavit, Mr. Cabrera García stated that, after he was beaten, “[his] genitals hurt a lot, […] they were very swollen, [he] could not keep [his] legs either open or closed.” Cf. Statement rendered by Teodoro Cabrera García before a public notary, supra note 147, pages 1194. For his part, in his testimony given before the Court at the public hearing held in this case, Mr. Rodolfo Montiel stated, inter alia, that one of the soldiers “pulled down [his] pants and underpants and they pulled […] [his] testicles” and that “at times, he lost consciousness.” Cf. Statement rendered by Mr. Rodolfo Montiel Flores at the public hearing held in this case. 178 Cf. Physicians for Human Rights- Denmark. Case of Messrs. Cabrera and Montiel, supra note 165, page 8381. 179 Cf. Physicians for Human Rights- Denmark. Case of Messrs. Cabrera and Montiel, supra note 165, page 8380. 180 The expert witness indicated that Mr. Cabrera García presented “a normal penis, an atrophied right testicle and a normal left testicle.” The atrophy “was confirmed during [his] physical evaluation and documented with an ultrasound of the testicular region in May 2010. The atrophy of the right testicle is consistent with testicular atrophy following trauma.” Regarding Mr. Montiel Flores, he stated that his “penis [was] normal [as well as] his testicles.” Cf. Expert report rendered by expert witness José Quiroga before a public notary, supra note 173, pages 1318, 1319 and 1326. 181 Cf. Expert report rendered by expert witness José Quiroga before a public notary, supra note 173, page 1319. 182 Cf. Expert opinion rendered by expert witness Juana Ma. Gutiérrez Hernández at the public hearing, supra note 35. 183 Cf. Statement rendered by Mr. Rodolfo Montiel Flores at the public hearing, supra note 177. 184 To this end, the Istanbul Protocol establishes that “[s]ome forms of torture such as electric shocks or blunt trauma may be initially undetectable, but may be detected during a follow-up examination.” However, “the type, time of application, current and voltage of the energy used cannot be determined with certainty upon physical examination of the victim. Torturers often use water or gels in order to increase the efficiency of the torture, expand the entrance point of the electric current on the body and prevent detectable electrical burns […].” Cf. Istanbul Protocol, supra note 149, paras. 174 and 211. 49