197. The Court has indicated that the investigation should be carried out by all legal means available 345 and conducted with due diligence. 346 The IACHR recalls that from the first steps the States are obligated to act diligently. 347 This is due to the fact that the first steps in an investigation are fundamental for the sound development of the judicial investigation. 348 Accordingly, the Court has noted: “All these requirements, together with criteria of independence and impartiality also extend to the non-judicial bodies responsible for the investigation prior to the judicial proceedings.” 349 198. The Inter-American Court took cognizance of two matters under its provisional measures mechanism in which two persons disappeared while they were being detained in prison. 350 The Court held that whenever there are reasonable grounds for suspecting that a person has been subjected to a disappearance it is essential for the prosecutorial and judicial authorities to act promptly and immediately. 351 This is for the purpose of ordering timely and necessary measures aimed at determining the victim’s whereabouts or where he or she may be found. 352 199. In addition, the Court noted that in situations of deprivation of liberty such as in the instant case, habeas corpus represents, among the essential judicial guarantees, the suitable means for determining the situation and whereabouts of the person disappeared, as well as to ensure respect for his or her life, and to protect his or her integrity. 353 The IACHR recalls that in cases of alleged disappearance “the mere formal verification of the official detainee records, as occurred in this case, or the acceptances as true of the denial of the detention by those presumably responsible, without an objective, impartial and independent verification, is neither reasonable nor diligent and does not constitute an effective remedy.” 354 Taking into account that the deprivation of liberty of a person in a mental health center may constitute an arbitrary detention in the terms of the Convention, the Commission considers that writs of habeas corpus may also be designed to address this kind of situation in which it is argued that there is a need to review deprivation of liberty in such centers and/or determine the fate or whereabouts of a person in custody as a result of an institutionalization such as that which occurred in the instant case. 200. In the instant case, the State’s duty to investigate was qualified, in terms of its nature and intensity, by several considerations. In the first place, it was qualified because it was a report of a disappearance that implied presuming the existence of a risk to the life and integrity of the person. Accordingly, having a prompt and diligent investigative response and search was fundamental not only for obtaining justice, but for protecting the life and integrity of Luis Guachalá. Second, it was qualified because it was the disappearance of a person with a disability institutionalized in a public mental health center with respect to whom the State was in a special position of guarantor. 201. The Commission observes that the report of the disappearance was filed on January 21, 2004, by Mr. Guachalá’s mother. The IACHR notes that the Office of the District Prosecutor of Pichincha (i) took the statements of Ms. Chimbó and hospital staff; (ii) conducted reconnaissance of the scene; and (iii) ordered autopsies of unidentified corpses. I/A Court HR. 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. 101. 346 I/A Court HR. Case of the brothers Gómez Paquiyauri v. Peru. Judgment of July 8, 2004. Series C No. 110, para. 146; and Case of Cantoral Huamaní and García Santa Cruz v. Peru. Judgment of July 10, 2007. Series C No. 167, para. 130. 347 I/A Court HR. Case of Zambrano Vélez et al. v. Ecuador. Merits, Reparations and Costs. Judgment of July 4, 2007. Series C No. 166. Para. 121. 348 I/A Court HR. Case of Myrna Mack Chang v. Guatemala. Judgment of November 25, 2003. Series C No. 101, para. 167. IACHR, Report No. 37/00, Case 11,481, Merits, Monsignor Oscar Arnulfo Romero y Galdámez, El Salvador, April 13, 2000, para. 85. 349 I/A Court HR. Case of Cantoral Huamaní and García Santa Cruz v. Perú. Judgment of July 10, 2007. Series C No. 167, para. 133. 350 See: I/A Court HR. Matter of Guerrero Larez with respect to Venezuela. Provisional Measures. Order of August 19, 2013; Matter of Natera Balboa with respect to Venezuela. Provisional Measures. Order of August 19, 2013. 351 I/A Court HR. Matter of Guerrero Larez with respect to Venezuela. Provisional Measures. Order of August 19, 2013, considering paragraph 6. 352 I/A Court HR. Matter of Guerrero Larez with respect to Venezuela. Provisional Measures. Order of August 19, 2013, considering paragraph 6. 353 I/A Court HR. Matter of Guerrero with respect to Venezuela. Provisional Measures. Order of August 19, 2013, considering paragraph 6. 354 I/A Court HR, Case of García and family v. Guatemala. Merits, Reparations and Costs. Judgment of November 29, 2012. Series C No. 258, para. 143. 345 37