investigation was conducted to clarify those differences, such as line-ups or other measures intended for this purpose. 118. The Commission stresses on this point that it is not its job to determine whether or not Lieutenant Coronel Morales is criminally liable or whether the homicide was out of willfulness or gross negligence, as this is the job of domestic criminal court judges. Notwithstanding, it is indeed the job of the Commission to determine whether or not the investigation and the criminal proceeding that determined how the crime was committed, fulfilled the obligations of the State under the American Convention. 119. In this regard, in the case of García Ibarra et al v. Ecuador, the Court established the relationship between an investigation conducted in breach of the duty of due diligence and the assessment of the facts. Specifically, the Court held that an assessment of the facts in the domestic arena, which is the product of a deficient investigation, does not constitute clarification of the facts under the requirement of the Convention. In the words of the Court on the case cited above: (…) the absence of the aforementioned investigation, or deficiently conducting any stage thereof, in order to substantiate contradictory versions of the deprivation of life, generated a lack of accurate and indispensable technical evidence with regard to said versions and did not genuinely strive to substantiate the whole truth about what happened, having a determinant bearing on the assessment of the facts set forth in the opinion of the judgment which was made final in said proceeding and, therefore, in the reasoning of the judgment. As such, the Court finds that the State is responsible for a lack of due diligence in the investigation of the facts relating to the instant case.124 120. As such and applying the above cited legal precedent to the instant case, the Commission considers that the decision finding Lieutenant Coronel Morales criminally responsible for negligent homicide was the result of a criminal investigation and proceeding that violated the protections of having a natural judge, independence, impartiality, as well as the duty to investigate with due diligence. In this regard, even though a final ruling was handed down in the domestic courts, because it was issued in a trial proceeding that was incompatible with the American Convention, said response of the State cannot be regarded as effective elucidation of the events nor as obtaining justice for the family of Mr. Trueba. 121. With regard to the punishment, the Commission recalls that it was a prison term of one year, eleven months and fifteen days. The Court has held that, in order to observe due process, the State must guarantee the principle of proportionality of punishment.125 Consequently, the punishment which the State assigns to the perpetrator of illicit conduct should be proportional to the rights recognized by law and the culpability with which the perpetrator acted, which in turn should be established as a function of the nature and gravity of the events.126 122. In the instant case and in the same vein as was set forth above, the imposition of the prison sentence of one year, eleven months and fifteen days was the result of an investigation and trial proceeding that violated the American Convention for a number of reasons that were examined earlier in the instant report. The Commission considered that the necessary evidence was not gathered in order to elucidate, among other things, whether or not Lieutenant Coronel Morales’s conduct was deliberate or not. On this score, the conclusion that led to the imposition of the punishment was not the result of an exhaustive investigation, but rather of the account of the military members present at the time, which was assumed to be true, while no effort was made at all to substantiate it through the expert witness studies required to do so. 124 IA Court of HR. Case of García Ibarra et al v. Ecuador. Preliminary Objections, Merits, Reparations and Costs. Judgment of November 17, 2015. Series C No. 306. Par. 143. 125 IA Court of HR. Case of the Massacre of La Rochela v. Colombia. Merits, Reparations and Costs. Judgment of May 11, 2007. Series C No. 163, par. 193. 126 IA Court of HR. Case of the Massacre of La Rochela v. Colombia. Merits, Reparations and Costs. Judgment of May 11, 2007. Series C No. 163, par. 196. 23