Agustín Contreras Santander and Manuel Valencia Cáceres died that day from a penetrating incised wound to the neck and a penetrating incised thoracic wound, respectively, as recorded in the Medical Death Certificates from the Legal Medical Institute.

The Autopsy Protocols specify that, in addition to the penetrating incised wounds, evidence of other injuries was found throughout their bodies, and that around their necks there was a wound 5 mm wide and 2 mm deep, caused by galvanized wire that was removed from their necks during the forensic examination.

According to statements from an eyewitness, Agustín Contreras and Manuel Valencia were detained by a group of military personnel on the night of September 9, 1974, at a bar located near their home, inside the Huamachuco neighborhood in the Renca commune. They were then taken to a unit of the Yungay Regiment, which was stationed in Quinta Normal at that time.

According to the witness, who was also apprehended on that occasion and later released, the detention occurred due to criticisms they had voiced aloud against the military regime. These were overheard by a soldier who was in the bar, who left to find other soldiers to arrest them.

Subsequently, their bodies were found by their relatives at the Legal Medical Institute, where they had been admitted as "NN" (unidentified).

An investigation into these events was initiated at the Second Military Prosecutor's Office of Santiago, which could not be examined as it has been lost. It was also impossible to verify whether those responsible for the deaths were convicted.

Nevertheless, the Corporation had access to a copy of a psychiatric examination issued by the Legal Medical Institute regarding the mental faculties of the soldier who reported them and who later participated in the detention, the original of which was sent to the aforementioned legal proceeding.

In the text of this expert report, the Prosecutor's Office is informed that this soldier admitted to having transported the detainees to the military facility, where he interrogated them by beating them with a stick, and that he later inflicted the wounds on them with a sharp weapon and strangled them with a wire.

The report warns that this soldier "presents characteristics of an explosive-type psychopathic personality and alterations that could be of epileptic origin."

Considering the evidence gathered and the investigation carried out by this Corporation, the Superior Council reached the conviction that Agustín Contreras Santander and Manuel Jesús Valencia Cáceres were executed outside of any legal process by State agents while they were being held in custody. By virtue of this, it declared them victims of human rights violations.