When Guadalupe Mejía began searching for her husband – a community leader who had been forcibly disappeared by Salvadoran armed forces in 1977 – it was Óscar Romero who encouraged her to speak out despite the danger.

“Unite and that’s how you’ll be able to find your loved ones,” Mejía, 75, remembers the archbishop of San Salvador telling her and other bereaved women. “He supported us and was always beside us in everything we did.”

Romero earned powerful enemies for speaking out against military death squads and advocating for the rights of the poor – and on 24 March 1980 he was shot dead while celebrating mass, marking the beginning of the country’s 12-year civil war.

On Sunday Romero officially became a saint.

But as Salvadorans celebrate his canonization, pride and joy are tempered with anger and pain: 75,000 people were killed during the civil war, the majority at the hands of the US-backed Salvadoran military.

An amnesty law rushed through after the end of the conflict guaranteed impunity for war crimes, and was only overturned in 2016. Prosecutions have moved slowly and there have been no convictions in a Salvadoran court.

“We still haven’t seen justice in any way,” said Marīa Irma Orellana, 64, whose sisters and two brothers were killed during the civil war. “We still feel this lack of justice in so many cases.”

Romero’s assassination is no different: nobody has ever been convicted of plotting or carrying out the murder – or the massacre that took place when troops fired into the crowd at his funeral, killing dozens of mourners.

A UN truth commission concluded that Roberto d’Aubuisson – an army officer and founder of the rightwing Arena party – was responsible for ordering the killing. D’Aubuisson, who died of cancer in 1992, was never tried in court.

Today, Romero’s bespectacled face is ubiquitous, gazing from postage stamps and posters across San Salvador.

But in life, he was a deeply divisive figure, reviled by rich Salvadorans as a “guerrilla in a cassock” – and after his death, Romero’s canonisation was bitterly resisted by conservative politicians and clerics, not least because of his association with the leftwing liberation theology movement.

Most rightwing politicians now make public displays of support for Romero’s canonization.

Arena presidential candidate Carlos Calleja has promised to support “a true search for truth” in the case. But the party still denies its founder was involved and in August celebrated what would have been d’Aubuisson’s 75th birthday.

The supreme court declared the amnesty law unconstitutional in 2016, and the following year, the María Julia Hernández Human Rights Association successfully pushed for the case of Romero’s murder to be reopened.

“Searching for justice in the case of Archbishop Romero also means dignifying all of the victims that he defended,” said Ovidio Mauricio García, the director of the association. “His case is the most emblematic because behind his case, there are even more victims and people who were assassinated, disappeared and tortured.”

Although the civil war ended in 1992, peace never came to El Salvador. US immigration policies helped street gangs originally formed in California take root in the country. Today, gang warfare, judicial impunity and political corruption have helped make it one of the most violent places on earth.

Mejía still awaits justice in the case of her husband’s disappearance – as does Orellana in the case of her siblings’ murders.

“He died, but he left his legacy for us,” Mejía said. “So that we can keep fighting and one day win what we seek – peace, justice and liberty.”

Sofía Hernández, who traveled to Rome to celebrate Romero’s canonization, said that nobody had ever been charged – let alone prosecuted – over the disappearances of her daughter, two siblings and four nephews.

“There are many of us victims and we want peace, justice and reparations,” she said over the phone from Rome. “We are going to continue fighting for our demands, so that the petitions of the victims are accepted. That’s what Romero taught us.”