196. Ms. J. was detained in the context of Operation Moyano, which, as previously established, was a carefully planned operation following an investigation of intelligence information (supra paras. 78 and 79). This reveals that an investigation was underway before the detention of Ms. J. of which she was not notified. In this regard, the State had indicated that “the notification of anyone simply meant the failure of the operation; the leadership of Shining Path could never have been captured, and especially the elimination of this terrorist group.” In this regard, the Court has indicated that in certain cases, it is admissible to keep the measures taken during an investigation in criminal proceedings confidential in order to guarantee the effectiveness of the administration of justice. The State has the power to build up a case file taking the necessary measures to prevent this task being impaired by the destruction or concealment of evidence. However, this power must be harmonized with the right of defense of the person investigated, which supposes the possibility of knowing the facts of which he or she is accused. 303 197. The information provided to the Court does not allow it to determine precisely when the investigation relating to Operation Moyano commenced, or whether Ms. J. had been individualized and identified as a person of interest or presumably related to El Diario before her arrest, so that it is not possible to determine whether she could have been notified of the investigation before her detention. However, the Court recalls that the transition between “investigated” and “accused” – and, at times, “convicted” – may occur suddenly, so that it is not possible to wait until someone is formally accused to provide him with the information on which the timely exercise of the right of defense depends. 304 198. In the instant case, Ms. J. was informed verbally of the reasons for her arrest during the search of the building on Las Esmeraldas Street (supra para. 150). However, this Court reiterates the obligation to notify the charges that have been brought promptly and in writing in keeping with Article 7(4) of the Convention persisted, even after the prosecutor of the Public Prosecution Service had advised the reasons for the arrest verbally (supra para. 151). In this regard, the Court notes that, even though, on April 14, 1992, Ms. J. was notified that she had been detained “to clarify the crime of terrorism (supra para. 92), there is no record in the case file that she was notified of the facts, causes and reasons that had led the State to make this accusation. The first statement that Ms. J. gave before a State authority was a police statement made on April 21, 1992 (supra para. 95), and there is no record that, prior to this statement, Ms. J. was advised in writing of the reasons for her detention, the reasons why the State brought the charge, the probative basis for this, and the legal definition of those facts, above and beyond the general and non-motivated notification that she was being investigated for the crime of terrorism. According to the information provided to the file of this case, the first documents in which Ms. J. or her lawyer would have been able to see in writing the reasons for her detention are the police attestation and the criminal complaint, both dated April 28, 1992 (supra paras. 97 and 98). 199. Furthermore, in order to satisfy Article 8(2)(b) of the Convention, the State must inform the interested party not only of the acts or omissions that he or she is accused of, but also of the reasons that led the State to bring the charges, the evidence for this, and the legal definition of the facts. All this information must be described explicitly, clearly, fully and in sufficient detail to allow the accused to exercise her right to defend herself fully and to explain her version of the facts to the judge. Even though the contents of the notification will vary according to the stage of the investigation, the persons investigated must be provided, at least, with the most detailed information possible on the facts attributed to them, and this information will be most complete when the final charges are officially filed. 305 This Court has established that, before making a 303 Cf. Case of Barreto Leiva v. Venezuela, supra, para. 45. 304 Cf. Case of Barreto Leiva v. Venezuela, supra, para. 46. 305 Cf. Case of Barreto Leiva v. Venezuela, supra, para. 31. 60