Short answers, pulled from the story.
Efraín Ríos Montt was a Guatemalan military officer who served as de facto president of Guatemala from 1982 to 1983 after a coup by junior military officers. His tenure was one of the bloodiest periods of the Guatemalan Civil War, during which the Guatemalan army's counter-insurgency campaign resulted in the annihilation of nearly 600 villages according to the UN-sponsored Historical Clarification Commission.
On the 10th of May 2013, a Guatemalan court convicted Ríos Montt of genocide and crimes against humanity and sentenced him to 80 years in prison. The Constitutional Court overturned the conviction ten days later on procedural grounds, and the retrial was not completed before he died of a heart attack on the 1st of April 2018.
Fusiles y Frijoles, rendered in English as "beans and bullets," was Ríos Montt's rural counter-insurgency plan. The "bullets" component organized Civil Defense Patrols of indigenous villagers, while the "beans" component sought to improve infrastructure and resources in Mayan villages to build civilian-military cooperation against the URNG guerrillas.
On the 8th of August 1983, Ríos Montt's own Minister of Defense, General Óscar Mejía Victores, overthrew him in a coup during which seven people were killed. The coup leaders alleged he belonged to a "fanatical and aggressive religious group" that threatened the separation of church and state. Historian Virginia Garrard-Burnett concluded the main underlying reason was that Ríos Montt had severely restricted the flow of graft to military officers and government officials.
The Reagan administration authorized the sale of $4 million in helicopter spare parts and $6.3 million in additional military supplies to the Guatemalan military in 1981. President Ronald Reagan met with Ríos Montt in San Pedro Sula, Honduras, on the 4th of December 1982 and publicly praised him. A then-secret 1983 CIA cable noted a rise in "suspect right-wing violence" and bodies appearing in ditches, but the U.S. continued the sale of helicopter parts throughout.
A group of junior military officers known as oficiales jóvenes staged a coup on the 23rd of March 1982, overthrowing General Romeo Lucas García. They chose Ríos Montt to lead the junta not because he planned the coup, but because of the respect he had earned as director of the military academy and as the democratic opposition's presidential candidate in 1974.