Rios Montt, who ruled Guatemala in 1982 and 1983 after a military coup, was convicted of genocide four years ago along with another military officer, but the ruling was overturned.
A Supreme Court tribunal will hear the case, Edgar Perez, a lawyer for the relatives of victims who have led a yearslong campaign against Rios Montt, said Wednesday.
The 91-year-old retired general was diagnosed with senile dementia in 2015. He will be represented in court by two lawyers and will not make a personal appearance. The lawyers were not immediately available for comment.
The new trial will revisit the earlier accusations that Rios Montt ordered massacres leading to deaths of at least 1,771 Ixil Mayan Indians during his 17-month rule. Rios Montt maintains his innocence, saying junior officers acted without his knowledge.
Guatemala's 1960-1996 civil war led to the deaths of more than 200,000 people and was the bloodiest among the Cold War conflicts that tore through Latin America when the U.S.-backed military government battled leftist governments and rebels.