file complaints, evidence or motions or any other procedure, in order to play a procedural role in the criminal investigation with the aim of establishing the truth of the facts.229. 145. The Court recalls that, in case of violence against women, the general obligations established in Articles 8 and 25 of the American Convention are supplemented and enhanced for the States parties by the obligations arising from the specific inter-American treaty, the Convention of Belém do Pará.230 Article 7(b) of this Convention specifically obliges States parties to apply due diligence to prevent, punish and eradicate violence against women.231 Also, Article 7(c) obliges States parties to enact the legislation required to investigate and punish violence against women.232 In such cases, State authorities must open, ex officio and without delay, a serious, impartial and effective investigation as soon as they become aware of facts that constitute violence against women, including sexual violence.233 Accordingly, when informed of an act of violence against a woman, it is particularly important that the authorities in charge of the investigation conduct this with determination and efficiency, taking into account society’s duty to reject violence against women, and the State’s obligation to eradicate it and to ensure that victims haves confidence in the State institutions established for their protection. 234 146. The Court has also indicated that the obligation to investigate is increased in the case of a woman who is killed or suffers ill-treatment, or whose personal liberty is violated in a general context of violence against women.235 In practice, it is often difficult to prove that a murder or a violent assault against a woman has been perpetrated based on her gender. At times this difficulty arises owing to the absence of a thorough and effective investigation into the violent incident and its causes by the authorities. This is why State authorities have the duty to investigate ex officio any possible discriminatory gender-based connotations in an act of violence perpetrated against a woman, especially when there are specific indications of sexual violence of some type, or evidence of cruelty inflicted on the woman’s body (mutilation, for example), or when this act occurs in a context of violence against women in a country or a particular region.236 Furthermore, the criminal investigation should include a gender perspective and be conducted by officials trained in similar cases and in attending victims of gender-based discrimination and violence.237 147. The Court has also established that, in cases of suspected gender-based murder, the State obligation to investigate with due diligence includes the duty to order, ex officio, the corresponding tests and expertise to verify whether the murder had a sexual motive or whether any type of sexual violence occurred. In this regard, the investigation into a presumed genderbased murder should not be restricted to the victim’s death, but should also include other specific violations of personal integrity, such as torture and acts of sexual violence. 238 In a Cf. Case of García Prieto et al. v. El Salvador. Preliminary objections, merits, reparations and costs. Judgment of November 20, 2007. Series C No. 168, para. 104, and Case of Veliz Franco et al. v. Guatemala, supra, para. 184. 230 Cf. Case of Fernández Ortega et al. v. Mexico. Preliminary objection, merits, reparations and costs. Judgment of August 30, 2010 Series C No. 215, para. 193, and Case of Espinoza Gonzáles v. Peru, supra, para. 241. 231 Cf. Case of Fernández Ortega et al. v. Mexico, supra, para. 193, and Case of Espinoza Gonzáles v. Peru, supra, para. 241. 232 Cf. Case of the Miguel Castro Castro Prison, supra, para. 344, and Case of Espinoza Gonzáles v. Peru, supra, para. 241. 233 Cf. Case of the Miguel Castro Castro Prison, supra, para. 378, and Case of Espinoza Gonzáles v. Peru, supra, para. 241. 234 Cf. Case of Fernández Ortega et al. v. Mexico, supra, para. 193, and Case of Espinoza Gonzáles v. Peru, supra, para. 241. 235 Cf. Case of González et al. (“Cotton Field”), supra, para. 293, and Case of Espinoza Gonzáles v. Peru, supra, para. 242. 236 Cf. Case of Veliz Franco et al. v. Guatemala, supra, para. 187. 237 Cf. Case of González et al. (“Cotton Field”), para. 455, and Case of Espinoza Gonzáles v. Peru, supra, para. 242. 238 Cf. Case of Veliz Franco et al. v. Guatemala, supra, para. 188. 229 53