In June 2001, a three-judge panel convicted retired Col. Byron Lima Estrada; his son, Capt. Byron Lima Oliva, and Sgt. Obdulio Villanueva of the bludgeoning death of Bishop Juan Gerardi. The three were sentenced to 30 years in prison each. The Rev. Mario Orantes, Gerardi's assistant, was sentenced to 25 years in prison as an accomplice.
On Tuesday, the appeals tribunal said the lower court had issued its verdict without adequately verifying the testimony of Ruben Chanax, whose statements were key to the convictions.
Gerardi was killed with a concrete block in the garage of his Guatemala City seminary in April 1998, days after presenting a lengthy report blaming the military for 80 percent of the deaths during the country's 1960-1996 civil war.
Activists had considered the convictions a human rights victory for a country that was plagued by thousands of atrocities. But the defendants appealed last month, claiming that police never found the person responsible for Gerardi's killing and accusing the trial judges of basing their ruling on speculation and hearsay instead of hard evidence.
The lawyers also attacked the testimony of Chanax, a homeless man who lived in a park across the street from the seminary. Chanax testified that the Limas and Villanueva hired him to spy on Gerardi, told him someone would die on the night of the killing and enlisted his help in altering the crime scene before police could arrive.
Following the convictions in July, the chief prosecutor and one of the judges that presided over the case left the country, saying they feared for their safety. During the nearly three-year probe into Gerardi's death, several prosecutors, witnesses and investigating magistrates quit the case or left Guatemala citing death threats.