Sofía Leonor Yáñez Calfupán died that day from a "deep cervical incised wound and asphyxia due to the application of a cervical ligature," as certified by the Autopsy Report.

According to witness statements and evidence gathered during the proceedings, the events occurred around 11:30 hours, while Sofía Yáñez was occupied with cleaning duties at her workplace in the commune of Ñuñoa. The perpetrators of the murder entered the home through a window and attacked her from behind with a utensil possibly taken from the kitchen, causing her death by throat-slitting.

Eyewitnesses stated that on that day, around 12:00 hours, they saw two people leaving in a suspicious manner, who were not identified in the judicial investigation. The evidence gathered in the case ruled out robbery as a motive, as the perpetrators did not steal items or valuables that could have been quickly and easily removed from the property.

Any resistance on her part against the perpetrators was also ruled out. The house was not in disarray; she was six months pregnant and was alone in the house at the time.

Sofía Yáñez did not engage in any type of political activity and was known for her affable and peaceful character.

The residence where she died belonged to a lawyer with a recognized track record in the defense of human rights and linked to the Vicaría de la Solidaridad of the Archbishopric of Santiago. Three months earlier, this professional had filed a writ of amparo on her behalf due to anonymous telephone threats she had been receiving at that same address.

For this reason, the Santiago Court of Appeals had ordered special police surveillance at her home for ten days. The lawyer was sponsoring a lawsuit for unlawful coercion and mistreatment of a political prisoner against officials of the Investigaciones police force. The office of the judge who was previously presiding over this case had been raided by unknown individuals.

Also, that same year, several lawyers publicly recognized for their professional work in the defense of human rights, likewise linked to the aforementioned organization, suffered various threats from unknown individuals, and some were the targets of repeated robberies at their private homes.

By virtue of the evidence gathered and the investigation carried out by this Corporation, the Superior Council, considering the manner of her death and the context in which it occurred, reached the conviction that Sofía Leonor Yáñez Calfupán was executed by State agents for the purpose of inhibiting the professional work carried out by the person for whom she worked.

For that reason, it declared her a victim of human rights violations.