Tiburcio Utuy was tortured at the hands of the Guatemalan military in early 1983, under the military dictatorship of Efrain Rios Montt. Three decades later, Tiburcio was among those who successfully brought about the prosecution of Rios Montt for genocide and other crimes in a Guatemalan court—a trial which ended in April with a guilty verdict being overturned by a legally questionable ruling by the country’s Constitutional Court.

Now Tiburcio is speaking out about his experiences once more, as Guatemalan civil society groups challenge the overturning of the Rios Montt verdict, in a petition before the Inter-American Commission on Human Rights in Washington D.C.

The Guatemalan military committed three massacres in Tiburcio’s community in early 1983, forcing him to flee to the mountains with hundreds of others. Attempting to forage for food, he was subsequently captured by the military and detained. In April 2013, as one of more than 90 witnesses testifying in a Guatemalan courtroom, he recounted being strung up, beaten, burned, interrogated, labeled a collaborator and paraded through a village as a guerrilla.

Other survivors, along with forensic and military experts, sociologists, statistical experts, and documentary and video evidence, depicted the scorched earth policy of the Guatemalan government under the 17-month rule of military strongman Efraín Ríos Montt.

At the end of a nearly two-month trial, a three-judge trial court found the former head of state guilty of genocide and crimes against humanity, and issued a 700-page judgment. It was the first time in history that a domestic court had ruled that a head of state committed genocide.

The genocide conviction was short-lived. Three days after the court issued its judgment, Guatemala’s Constitutional Court annulled the verdict in a divided ruling. Essentially on a technicality, ignoring standard processes and without even acknowledging that the trial court had issued a verdict or considering the merits, the Constitutional Court set the trial back to its midpoint.

The Constitutional Court decision created a legal morass. Having already issued a verdict, the trial court recused itself from any further action in the case. Dozens of judges refused to enforce the decision. Only this week, a new trial court set a date to re-start the trial for 2015. Further, last month, the Constitutional Court also re-opened the question of whether a historic amnesty—decreed by the strongman who succeeded Ríos Montt—should prevent his prosecution.

The survivors have petitioned the Inter-American Commission to challenge continuing impunity for these decades-old atrocities in Guatemala. The Commission, an organ of the Organization of American States focused on the protection of human rights, has recognized repeatedly the obligations of states to investigate and prosecute grave crimes, and rejected amnesty for international crimes. The Commission has in particular excoriated so-called self-amnesties, granted by dictators to protect themselves from accountability.

Under the leadership of Guatemala’s pioneering attorney general, Claudia Paz y Paz, Guatemala has begun to make inroads on a culture of near-total impunity. This previously unimaginable trial exists along similar monumental advances that include significant improvements in homicide, corruption and narco-trafficking prosecutions. But the questionable annulment of the verdict, the consideration of amnesty for grave crimes, and growing threats to corrupt next year’s process to name judges and Guatemala’s attorney general demonstrate the weaknesses which remain.