41.Based on principles of international law, the precedents established by the Commission, and the case-law of the Inter-American Court, the respondent State may waive, either expressly or tacitly, its right to invoke this rule. 2 Secondly, for the exception of non-exhaustion of remedies available under domestic law to be applicable, it must be raised during the early stages of the proceedings before the Commission, and if this is not the case, the State concerned will be assumed to have tacitly renounced its right to invoke it. 3 Thirdly, in line with the burden of proof applicable in the case, a State that alleges non-exhaustion must indicate which remedies were available under domestic law to be exhausted and provide evidence of their effectiveness. 4 Consequently, if the State in question fails to lodge its allegations regarding this requirement at the appropriate time, it will be considered to have renounced its right to allege the non-exhaustion of remedies available under domestic law and therefore to satisfy the appropriate burden of proof. 42.In the present case, the State has not responded to the initial petition, and therefore has tacitly renounced its right to lodge an exception to the non-exhaustion of remedies available under domestic law. The petitioners, for their part, allege there has been an unwarranted delay in the criminal proceedings and therefore claim that the exception set out in Article 46(2((c) of the American Convention is applicable. 43.To assess how far the requirement to exhaust remedies available under domestic law has been met, the Commission must determine which is the appropriate remedy that should be exhausted in the circumstances, understanding this as that remedy which is able to solve the juridical situation that has been infringed. In cases of alleged arbitrary infringements of the right to life, the appropriate remedy is the criminal investigation and proceedings brought and driven by the State in order to identify and punish those responsible. 44.In relation to the unwarranted delay, the Commission examines the circumstances and makes a case-by-case evaluation in order to decide whether or not there has been an unwarranted delay. As a general rule, the Commission states that “a criminal investigation should be carried out promptly in order to protect the interests of the victims and to preserve the evidence.” 5 To determine whether or not an investigation has been carried out “promptly”, the Commission must evaluate a series of factors such as the time elapsed since the offense was committed, if the investigation has progressed beyond the initial stages, the steps taken by the authorities, and the complexity of the case. 6 45.As demonstrated by the petitioners, the internal judicial proceedings launched by the State have not progressed beyond preliminary investigations even though the events took place between December 29 and 30, 1996, that is, more than 10 years ago. The Commission also observes that the case is not especially complex in view of the fact that it deals with one victim executed in circumstances in which police officers, in whose custody he was, have been clearly identified. Furthermore, information supplied by the petitioner and unchallenged by the State, indicates that investigations have been frozen for long periods of time even though Mr. Ignacio Landaeta Muñoz has played an active role, to the extent of requesting the completion of certain measures. This has been the case in spite of the fact that the exclusive responsibility 2 IACHR, Report No. 69/05, petition 960/03, Admissibility, Iván Eladio Torres, Argentina, October 13, 2005, paragraph 42; I/A Court H.R, Ximenes Lopes Case. Preliminary Exceptions. Judgment November 30, 2005. Series C No. 139, paragraph 5; I/A Court HR, Moiwana Community Case. Judgment June 15, 2005. Series C No. 124, paragraph 49; and I/A Court HR, I/A Court HR, Case of the Serrano Cruz Sisters. Preliminary Exceptions. Judgment November 23, 2004. Series C, No 118, paragraph 135 3 I/A Court HR, Mayagna Community (Sumo) Awas Tingni Case. Preliminary Exceptions. Judgment February 1, 2000. Series C No 66, paragraph 53; Castillo Petruzzi and Others Case. Preliminary Exceptions. Judgment September 4, 1998. Series C, No 41, paragraph 56; and I/A Court H.R., Loayza Tamayo Case.Preliminary Exceptions. Judgment January 31, 1996. Series C No 25, paragraph 40. The Commission and the Court have said that “the first stages of a process” should be understood as “at the admissibility stage before the Commission, that is, before any consideration of the merits […]”. See, for example, IACHR, Report No. 71/05, petition 543/04, Admissibility Ever de Jesús Montero Mindiola, Colombia, October 13, 2005, which quotes I/A Court H.R., Herrera Ulloa Case. Judgment July 2, 2004. Series C, No 107, paragraph 81 4 IACHR, Report No. 32/05, petition 642/03, Admissibility, Luis Rolando Cuscul Pivaral and other persons affected by HIV/AIDS, Guatemala, March 7, 2005, paragraphs 33-35; I/A Court H.R., Mayagna Community (Sumo) Awas Tingni Case.Preliminary Exceptions, supra note 3, paragraph 53; Durand and Ugarte Case. Preliminary Exceptions. Judgment May 28, 1999. Series C, No. 50, paragraph 33; and Cantoral Benavides Case. Preliminary Exceptions. Judgment September 3, 1998. Series C, No. 40, paragraph 31 5 6 IACHR, Report 16/02, Servellón García, Honduras, Petition 12,331, Admissibility, paragraph 31 (February 27, 2002) IACHR, Report No. 130/00, Victor Manuel Oropeza, Mexico, Petition 11,740, paragraphs 30-32. 6