A Guatemalan court ruled on Monday that former US-backed dictator Jose Rios Montt will stand trial for the murder, torture and displacement of thousands of Mayan Indians.
Judge Miguel Angel Galvez ruled that Rios Montt could be tried on charges of genocide and crimes against humanity for the killing of 1,771 indigenous Ixiles in 1982 and '83, when he was president.
Human rights activists said the prosecution would be an important symbolic victory for the victims of the horrific conflict.
"It's the beginning of a new phase of the struggle," said International Centre for Transitional Justice vice-president Paul Seils.
It was "a good step forward" but he expected the prosecution to be resisted by those who want to ensure government-allied forces go unpunished.
"The fact that a judge has ordered the trial of a former head of state is a remarkable development in a country where impunity has long been the norm," said Human Rights Watch Americas director Jose Miguel Vivanco.
Guatemala's leaders have been criticised for years for their unwillingness to prosecute government forces and paramilitaries accused of marching into Mayan villages, raping, torturing, slaughtering women, children and unarmed men in a scorched-earth campaign aimed at eliminating support for a left-wing guerilla movement.
Despite several international inquiries finding him responsible for war crimes, Rios Montt served as a congressman for 15 years until he lost an election last year.