Højre-generalen Rios Montt førte et rædselsregime i Guatemala i Mellemamerika og står nu anklaget for forbrydelser mod menneskeheden i form af massedrab på 1.771 maya-indianere i 1982-83.
Prosecutors said he wanted to wipe out the indigenous group, which he suspected of supporting rebel fighters, reports BBC online Monday.
General Efrain Rios Montt, 86, is the first ex-president to be charged with genocide (folkedrab) by a Latin American court.
The ruling clears the way for a three-judge panel to try the former president and another former military man, Jose Mauricio Rodriguez.
Gen Rios Montt had enjoyed immunity from prosecution for 12 years while he was serving as a congressman.
The immunity was lifted on 14 January 2012, when his term ran out. He has been under house arrest since.
Gen Rios Montt will also face charges over the forced displacement of 29.000 indigenous Guatemalans (fra indfødte folkeslag) as part of what human rights groups have called his “scorched earth” (brændte jords) policy.
The ruling is a significant victory for human rights advocates who have been pressing for his trial since the end of the civil conflict in 1996.
An estimated 200.000 people were killed or went missing during the 36-year conflict.
Gen Rios Montt’s 17 months in power are believed to have been one of the most violent periods of the war.
