Chilean judicial officials vowed to investigate the death of President Salvador Allende for the first time, 37 years after the socialist leader was found shot through the head with a machine gun during an attack on the presidential palace.
Mr Allende died during the September 11, 1973, coup led by General Augusto Pinochet, who governed as a dictator until March 11, 1990, and died in 2006.
Authorities have never before opened a criminal probe of Mr Allende's death, which many believe to have been a suicide.
Chile's truth commission reported in 1991 that the Pinochet dictatorship killed 3,797 people. Most of those cases have been investigated, leading to human rights trials for some 600 military figures and a small number of civilian collaborators.
About 150 have been convicted, including feared secret police chief Miguel Contreras, now imprisoned for dozens of crimes against humanity. But 726 deaths were never investigated, including Mr Allende's.
Beatriz Pedrals, a prosecutor in the appellate court in Santiago, said she decided to probe all the cases arising from the truth commission report that were never prosecuted. In some instances, survivors did not want to press charges. Others simply fell through the cracks.
"What wasn't investigated, the justice system will investigate," Ms Pedrals said. "This will be resolved in the proper manner."
The work now falls to Mario Carroza, an experienced investigative judge who already is handling hundreds of other human rights cases.
Judge Carroza described it as "work that is more than important, a tremendous responsibility".
He told reporters that he would seek information from a variety of sources, including a judge now investigating the deaths of Mr Allende's comrades, who disappeared after surrendering to the military outside the palace.