diligent and effective responsibility.198 investigation also gives rise to the State’s international 191. With regard to compliance with the obligation to investigate, the Court emphasizes the importance of effectively and diligently investigating human rights violations perpetrated against journalists in relation to the exercise of their freedom of expression, whether these acts were committed by State agents or private individuals, as this will help prevent their repetition (infra para. 247). 192. In the instant case, the State accepted that “no serious investigation was conducted” into the threats and harassment; however, in this regard, it only acknowledged having violated the right to judicial guarantees and judicial protection (supra para. 14(c)). The Court considers that the lack of a diligent investigation into the threats and harassment also involved a violation of the obligation to guarantee the right to personal integrity of Mr. Vélez Restrepo, his wife and children and, in turn, constituted a violation of the obligation to prevent since in this case the investigation could have been a means to prevent the continuation and escalation of the threats that went so far as an attempted deprivation of liberty of Mr. Vélez, which caused him to have to leave the country to protect his life and integrity. 193. Furthermore, with regard to the State’s obligation to adopt special measures of prevention and protection, the Court considers that the context of risk for journalists in Colombia (supra para. 84) should have been taken into account by the State authorities to make a diligent evaluation of the need for opportune measures of protection for Mr. Vélez Restrepo and his family. In this regard, the Court also takes into account the opinion of expert witness Tulande, proposed by the State, who explained the factors that have an impact on the level of danger faced by the journalists at the time of the facts of this case.199 In addition, according to expert witness Tulande, the situation of the journalists was such that it warranted the adoption, in 1995, of a law to create a special protection unit for members of professions who experienced permanent risk, including journalists, which “could be fully implemented in 2002.” 194. In this regard, the Court considers it important to indicate that States have the obligation to adopt special measures of prevention and protection for journalists subject to special risk owing to the exercise of their profession. Regarding the measures of protection, the Court underlines that States have the obligation to provide measures to protect the life and integrity of the journalists who face this special risk owing to factors such as the type of events they cover, the public interest of the information they disseminate, or the area they must go to in order to do their work, as well as to those who are the target of threats in relation to the dissemination of that information or for denouncing or promoting the investigation of violations that they suffered or of those they became aware of in the course of their work. The States must adopt the necessary measures of protection to avoid threats to the life and integrity of journalists under those conditions.200 198 Cf. Case of Velásquez Rodríguez v. Honduras. Merits, supra note 18, paras. 162, 166 and 176, and Case of the Barrios Family v. Venezuela, supra note 77, paras. 173 and 174. 199 Expert opinion provided by José Francisco Tulande during the public hearing before the Inter-American Court on February 24, 2012. 200 Regarding the obligation to implement measures of protection for journalists who are working in a context of armed conflict or serious disruption of public order, Cf. Inter-American Commission on Human Rights, Office of the Special Rapporteur for Freedom of Expression, The Inter-American Legal Framework regarding the Right to Freedom of Expression, CIDH/RELE/INF.2/09, December 30, 2009, paras. 195 and 196. Similarly, with regard to human rights defenders, cf. Case of Nogueira de Carvalho et al. v. Brazil. Preliminary objections and 58