Former Guatemalan strongman Efraín Ríos Montt went on trial in Guatemala City late last month on charges of genocide relating to the massacres of indigenous Mayan people during his rule.

The trial of a former dictator is a remarkable development in a country where impunity for past atrocities has long been the norm. But it also confirms a heartening trend toward bringing to justice the perpetrators of the worst atrocities, no matter how long ago the acts were committed. Indeed, Ríos Montt is the third former dictator in less than two months to face charges stemming from crimes committed in the 1980s and earlier.

On February 28, the former Haitian “President for Life,” Jean-Claude “Baby Doc” Duvalier, was forced to answer questions by an appeals court looking into allegations of human rights crimes committed during his rule, from 1971 to 1986. On February 8, meanwhile, Senegal and the African Union inaugurated special chambers within the Senegalese justice system to try crimes committed under the 1982 to 1990 rule of the exiled former dictator of Chad, Hissène Habré.

In each case, the breakthrough was achieved in large part thanks to the courage and perseverance of victims who never gave up hope. I’ve seen the tenacity of the Chadian and Haitian victims up close. Souleymane Guengueng, who almost died from dengue fever during two and a half years in Habré's jails and who watched dozens of cellmates die, took an oath that if he got out alive, he would fight for justice. When Habré was overthrown and fled to Senegal, Guengueng rallied wary survivors and widows and went to Senegal to press charges.

Although a Senegalese judge indicted Habré in 2000, former President Abdoulaye Wade found one pretext after another to delay Habré's reckoning, turning his victims' saga into what Bishop Desmond Tutu described as an "interminable political and legal soap opera." When threats from Habré's henchmen back in Chad forced Guengueng into exile, his lawyer, Jacqueline Moudeina, carried on the fight – despite the shrapnel still in her leg from a grenade thrown at her in 2001 on the orders of one of Habré's security chiefs, who had returned as police chief of Chad's capital.

When Duvalier’s surprise return to Haiti in early 2011 after 25 years in exile was followed by the election of President Michel Martelly, who spoke openly of pardoning Duvalier, most people gave up hope of justice in a country where the rich and powerful have always anyway been above the law. But a small group of victims engaged the judicial system through seemingly quixotic complaints. “I refuse to allow fear to return to Haiti” explained Michèle Montas, a former radio journalist who was illegally arrested and exiled. Boby Duval, who counted 180 people who died in his small cell in the notorious Fort Dimanche prison, and whose schools now educate and feed thousands of poor Haitian children, said, “I owe it to the young people to remember what happened.”

The same is true in Guatemala. According to Kate Doyle of the National Security Archive, who has helped the victims build their case, it was “the sustained and determined efforts of the Mayan communities over 30 years” that kept the case alive. In a country where those who seek justice for state-sponsored crimes have themselves often been killed, witnesses told their stories hundreds of times and helped unearth the remote mass graves left by Ríos Montt’s troops.

It takes a little more than the will of the victims, of course. Last year, the election of a new Senegalese President, Macky Sall, and a binding order from the International Court of Justice to Senegal to bring Habré to justice “without further delay,” changed the fate of the case. In Haiti, the appeals court judges showed unexpected backbone in issuing a warrant for Duvalier’s appearance. In Guatemala, the ascension of a courageous attorney general, Claudia Paz y Paz, supported by the international community, was the final touch that allowed the Ríos Montt case to go forward. That international support will remain essential through the trial.

After he finished testifying against Duvalier, Boby Duval told me, “Everyone said I was wasting my time, but I wasn’t wasting my time.” It was almost exactly what Souleymane Guengueng said when Senegal established the Habré court: “When I began 22 years ago, everyone thought I was crazy. But we have shown them that justice is possible.”

Let’s hope that the Guatemalan victims can say the same when the Ríos Montt trial is over.