Rios Montt is accused of being responsible for the murders of 1,771 indigenous Ixil-Maya people during his short reign, which came at the height of a brutal 36-year civil war.
By doing so, Guatemala will follow the lead of its major ally, the United States.
The trial will examine a US$35 million public contract made in 2009 for the purchase of hundreds of buses to ply routes in San Salvador.
By following the US' lead in recognizing Jerusalem as Israel's capital, Guatemala has deepened its alliance with the US, but has also risked angering many other countries.
Guatemala menyertai segelintir negara yang mengundi menolak resolusi PBB.
Guatemala and neighbouring Honduras were two of only a handful of countries to join Israel and the United States, which has pledged to move its embassy to Jerusalem, in voting against the UN resolution.
Millicom International Cellular's Guatemala City unit has been searched by government and United Nations-backed authorities due to alleged corruption.