54 3. Legal classification 133. The Court has indicated that the violation of the right to physical and psychological integrity of persons is a category of violation that has several gradations and embraces treatment ranging from torture to other types of humiliation or cruel, inhuman or degrading treatment with varying degrees of physical and psychological effects caused by endogenous and exogenous factors (such as, inter alia, length of the treatment, age, sex, health, context and vulnerability, among others), which must be proven in each specific situation. Likewise, the Court specified that any use of force that is not strictly necessary to ensure proper behavior on the part of the detainee constitutes an assault on the dignity of the person in violation of Article 5 of the American Convention.199 134. In this case, the lack of an investigation against the alleged perpetrators of the violation of the right to humane treatment [personal integrity] limits the possibility of concluding on the allegations of the alleged torture committed against Messrs. Montiel and Cabrera. Without prejudice to the foregoing, the Court has mentioned that the State is responsible, in its conditions of guarantor of the rights enshrined in the Convention, for the observance of the right to humane treatment of every person under its custody.200 The case law of this Tribunal has also pointed out that the State must provide a satisfactory explanation for what has happened to a person whose physical conditions were normal when custody began, and during it or at the end of it this worsened.201 Consequently, it is possible to consider that the State is responsible for the injuries exhibited by a person who has been in the custody of State agents.202 In said case, it falls upon the State the obligation to provide a satisfactory and convincing explanation of what happened and disprove the allegations regarding its responsibility, using adequate supporting evidence.203 Therefore, the Court highlights that from the evidence presented in the case, it is possible to conclude that cruel, inhuman and degrading treatment were proved against Messrs. Cabrera and Montiel. 135. In light of the above, this Court reiterates that whenever there are indications that torture has taken place, the State must initiate, ex officio and immediately, an impartial, independent and meticulous investigation that allows the nature and origin of the injuries observed to be determined, those responsible to be identified and their prosecution to commence.204 It is essential that the State act diligently to avoid the practice of torture or cruel, inhuman and degrading 199 Cf. Case of Loayza Tamayo v. Perú, supra note 37, para. 57; Case of Miguel Castro-Castro Prison v. Perú. Interpretation of the Judgment on the Merits, Reparations and Costs. Judgment of August 2, 2008. Series C N° 181; para. 76. 200 Cf. Case of López Álvarez V. Honduras. Merits, Reparations and Costs. Judgment of February 1, 2006. Series C N° 141, paras. 104 to 106; Case of the Miguel Castro Castro Prison v. Perú. Merits, Reparations and Costs. Judgment of November 25, 2006. Series C N° 160, para. 273; Case of Ibsen Cárdenas and Ibsen Peña v. Bolivia, supra note 30, para. 117. 201 Cf. Case of Juan Humberto Sánchez v. Honduras, supra note 119, para. 100; and Case of Bulacio v. Argentina, supra note 123, para. 127. 202 Cf. Case of the “Street Children” (Villagrán Morales et al) v. Guatemala; supra note 29, para. 170; and Case of Escué Zapata v. Colombia, supra note 53, para. 71; Case of Ibsen Cárdenas and Ibsen Peña v. Bolivia, supra note 30, para. 95. 203 Cf. Case of Juan Humberto Sánchez v. Honduras, supra note 119, para. 111, Case of the Miguel Castro-Castro Prison v. Perú. Merits, Reparations and Costs. Supra note 200, para. 273; and Case of Zambrano Vélez et al v. Ecuador, supra note 24, para. 108. 204 Cf. Case of Gutierrez Soler v. Colombia. Merits, Reparations and Costs. Judgment of September 12, 2005. Series C No. 132, para. 54; Case of Bayarri v. Argentina, supra note 123, para. 92; Case of Bueno Alves v. Argentina. Merits, Reparations and Costs. Judgment of May 11, 2007. Series C No. 164, para. 88.