357. The State also indicated that it had acted with due diligence during the different visits to inspect Hacienda Brasil Verde and that, during the said inspections, the State agents had performed their functions adequately and determined that slave labor was not practiced and nor were there conditions similar to slavery. 358. In addition, the State indicated that there were elements that justified the delay in the criminal proceedings initiated in 1997, and that these referred to factors of special complexity. For example, the accused lived in towns other than the place where the criminal action was filed; the authorities were unaware of Mr. Quagliato Neto’s domicile; the geographical distance made it complicated to obtain evidence, and there was “absolutely no legal definition” of the who had competence to process the crime of reduction to conditions similar to slavery. 359. The State indicated that the investigation procedures conducted by the Public Prosecution Service were adequate and effective mechanisms for criminal investigations and prosecutions. It indicated that the inspections conducted in Hacienda Brasil Verde had not led to the conclusion that slave labor existed, and that the administrative infractions verified, such as degrading conditions and extenuating working days, could not be characterized as crimes under the laws in force at that time. 360. Lastly, the State argued that the Public Prosecution Service had competence to conduct autonomous criminal investigation procedures, as in this case, and these procedures should also be considered adequate and effective remedies for the investigation of crimes that represent violations of the American Convention. B. Considerations of the Court 361. Before beginning to analyze the arguments, the Court recalls that, in this case, its contentious jurisdiction is limited to the judicial actions that began or have continued since the State’s acceptance of this jurisdiction on December 10, 1998. The Court will not examine the proceedings that took place in 1989, 1992, 1993 and 1996 because they had concluded before the State accepted the Court’s jurisdiction; nevertheless, it may take them into account as context. Accordingly, in this chapter, the Court will analyze the actions taken after December 10, 1998: (i) in criminal proceeding No. 1997.39.01.831-3 and the public civil action, both initiated in 1997, in relation to the inspection of March 10, 1997, and (ii) the proceedings initiated by virtue of the inspection of March 15, 2000. B.1. Due diligence 362. The Court recalls that, since protection against slavery and conditions similar to slavery is an international obligation erga omnes (supra para. 249), derived from the principles and rules concerning the basic rights of the human being, when States are aware of an act that constitutes slavery, servitude or trafficking, in the terms of Article 6 of the American Convention, they should open ex officio the pertinent investigation in order to establish the corresponding individual responsibilities.479 363. In this case, the State had an obligation to act with due diligence and this was increased owing to the gravity of the facts that had been reported and the nature of the obligation. The State should have acted diligently to prevent the facts remaining unpunished, as occurred in this case. 479 Cf. Case of the Río Negro Massacres, para. 225. 91