74 discriminatory motives for an act of violence against a woman may constitute, in itself, a form of gender-based discrimination. 209. According to certain international standards sexual violence,315 evidence relating to the sexual principle; hence, opening lines of investigation into the victims in cases of gender violence is merely based on gender stereotypes. concerning violence against women and history of the victim is inadmissible, in the previous social or sexual behavior of a manifestation of policies or attitudes 210. As already demonstrated in this case, the authorities in charge of the investigation failed to obtain pertinent evidence to determine that sexual violence had occurred, or obtained this belatedly when the probative elements, whose chain of custody had not been safeguarded, had been contaminated (supra para. 196.b). In addition, the Court considers that the lack of due diligence in the investigation of the victim’s murder is closely related to the absence of specific norms or protocols for the investigation of cases of the gender-based murder of women and violence against women in general. As the State has acknowledged, at the time of the events, there were no specific laws or procedures for investigating cases of violence against women. The State adopted most of the laws and measures for combating this phenomenon after the events of this case,316 so that it has not been possible to apply them to it, and they have not helped to make the investigation into the death of María Isabel Veliz Franco more effective. The foregoing could partly explain the State’s negligence, but cannot justify it or exempt the State from international responsibility. And this is because the norms on which the rights and obligations examined herein are based require their full and immediate observance by the State as of the entry into force of the respective treaties. Consequently, the Court cannot admit the State’s argument that it is exempted from responsibility because the State authorities took all the pertinent measures under the laws in force at the time and to the best of their ability. 211. Additionally, the difficulties to establish whether María Isabel Veliz Franco was a victim of violence against women according to the Convention of Belém do Pará result, in part, from the absence of a thorough and effective investigation by the State authorities into the violent incident that led to the victim’s death, as well as its possible causes and motives. The Court has already indicated that, in 2001, at the time of the events, a context of an increase in murders involving acts against women existed in Guatemala (supra para. 81); to this can be added the fact that, in this case, there was sufficient evidence to suspect that the victim’s murder could have had a discriminatory motive, owing to hatred or contempt based on her condition as a woman, or that it was perpetrated with some kind of sexual violence (supra paras. 178 and 196.b and infra para. 225). In addition, the judicial case file reveals that Rosa Elvira Franco Sandoval informed the Prosecutor General and Head of the Public Prosecution Service that when she went to the morgue to identify her daughter, the forensic physician “told her that her daughter had been raped” (supra para. 98). 212. This failure to comply with the obligation of non-discrimination was increased in this 315 Article 54 of the Council of Europe Convention on preventing and combating violence against women and domestic violence establishes that: “Parties shall take the necessary legislative or other measures to ensure that, in any civil or criminal proceedings, evidence relating to the sexual history and conduct of the victim shall be permitted only when it is relevant and necessary.” Cf. Council of Europe Convention on preventing and combating violence against women and domestic violence supra, art. 54. In its Rules of Procedure and Evidence, the International Criminal Court has also ruled on the importance that consent cannot be inferred from the victim in cases of sexual violence. Thus, for example, “[c]redibility, character or predisposition to sexual availability of a victim or witness cannot be inferred by reason of the sexual nature of the prior or subsequent conduct of a victim” and “a Chamber shall not admit evidence of the prior or subsequent sexual conduct of a victim.” Cf. International Criminal Court, Rules of Procedure and Evidence. 316 Law against Femicide and all forms of Violence against Women (2008); Law against Sexual Violence, Exploitation and People Trafficking (2009); creation of courts and tribunals with competence in cases of femicide and all forms of violence against women (2010), and specific protocols for the proper recovery of corpses (used by the National Institute of Forensic Science).