Death of Eduardo Frei Montalva

Eduardo Frei Montalva served as President of Chile from 1964 to 1970 and later became an opposition figure who initially supported the 1973 coup that deposed President Salvador Allende and installed the military government led by Augusto Pinochet. In 1981, Frei sought treatment for a hiatal hernia causing chronic acid reflux. He underwent surgery at the Santa María Clinic in Santiago on November 18, 1981, performed by a team including Dr. Augusto Larraín Orrego, Dr. Patricio Silva Garín, and Dr. Ivo Eterovic. After initial improvement and discharge, Frei developed fever and pain and was readmitted on December 4, 1981, where he was diagnosed with intestinal occlusion and partial necrosis of the small intestine. A second surgery was performed on December 6, 1981, by Dr. Silva Garín. Frei's condition again deteriorated; he developed septic shock and septicaemia, followed by immune system collapse, and died on January 22, 1982. His death was initially attributed to infection by Candida albicans.

Controversy over the cause of death emerged from allegations that Frei was poisoned by DINA, the intelligence service of the military government, using a toxin allegedly produced by biochemist Eugenio Berríos. Reports that Belgian researchers from the University of Ghent had found biological remnants of mustard gas in Frei's remains prompted his family to file a lawsuit, which was still pending as of 2009. Frei's personal physician, Patricio Rojas, who later served as a government minister, denied the poisoning allegations, and columnist Hermógenes Pérez de Arce disputed the existence of the Belgian report entirely.

In December 2009, six individuals were arrested in connection with the alleged assassination. Judge Alejandro Madrid's investigation concluded that Frei had been administered low doses of thallium and mustard gas over an extended period during hospitalization, weakening his immune system. This finding faced criticism from the medical team involved in the original surgeries and on scientific grounds. Legal proceedings continued over the following years: on October 10, 2014, two defendants were found guilty as perpetrators, two as accomplices, and two for covering up the alleged operation. On January 30, 2019, all six defendants were convicted of homicide, receiving sentences of three to ten years in prison.

These convictions were subsequently overturned. On January 25, 2021, a three-judge panel of a Chilean Appeals Court reversed the convictions, concluding that Frei was not a homicide victim. The Chilean Supreme Court affirmed this finding on August 18, 2023. Separately, in April 2013, the body of poet Pablo Neruda—who died at the same clinic one day before he was to depart into exile—was exhumed amid suspicions of foul play in his death; that case was related but distinct.