The trial of one-time dictator José Efraín Ríos Montt is barely underway in a Guatemalan courtroom, but it already constitutes a historic milestone: the first time that a former head of state has been put on trial for genocide by a national tribunal.

That the trial is taking place at all is a remarkable tribute to prosecutors and those who have doggedly been seeking justice for decades. Up to now it has been unheard of for anyone in authority in Guatemala, a country with a sad history of violence and racism against indigenous Mayans, to be held accountable for human rights abuses.

One of the worst periods came during the civil war, in which some 200,000 people died and 45,000 disappeared during a 36-year period that ended in 1996. A U.N.-backed truth commission later blamed the army and paramilitary groups for more than 90 percent of the hundreds of massacres during the war.

Gen. Ríos Montt, installed after a military coup in 1981, held power during one of the most violent eras, when soldiers carried out a “scorched earth” campaign that, prosecutors say, resulted in the deaths of at least 1,771 Ixil Mayans. Prosecutors hold Gen. Ríos Montt responsible and hope to prove their case using hundreds of witnesses, documents and videos, including the dictator’s own words.

The trial sends a much-needed message across Latin America: Even in those countries with the most violent histories, leaders (from the right or the left) who commit atrocities against their people will one day be forced to face justice.