The impunity surrounding the March 24, 1980, assassination of a Salvadoran archbishop will be a stain on his upcoming canonization, an attorney for the organization that secured a reopening of the murder case last year said in an interview with EFE.

Oscar Romero, who was the archbishop of El Salvador's capital, San Salvador, was killed while celebrating Mass by a right-wing death squad at the start of that Central American nation's 1980-1992 civil war.

"There will be a dark side to his canonization, which is the impunity," and "you hope it won't be left to the next generations" to resolve, Alejandro Diaz said, adding that progress in the case has been very slow since it was reopened in May 2017.

Diaz, a member of the Maria Julia Hernandez Legal Office, a human rights organization, said the Salvadoran courts needed to follow the lead of the Catholic Church under Pope Francis and make amends for past wrongs.

Romero, whose canonization process had been stalled until 2013 because he was seen as holding far-left political views, is remembered for homilies in which he denounced government repression of the poor.

But Diaz said Romero "never had any (ideological) inclination and only defended human rights."

On May 18, 2017, a Salvadoran judge reopened the murder case and ordered that charges be brought against the main suspect, Alvaro Rafael Saravia, whose whereabouts are unknown.

That decision came less than a year after El Salvador's Supreme Court overturned a 1993 law providing amnesty for war crimes during the civil conflict, which pitted government forces against the Farabundo Marti National Liberation Front (FMLN) guerrilla coalition.

But Diaz said it was important that the investigation be expanded to include other suspects, particularly individuals mentioned in a 1993 United Nations truth-commission report as having masterminded the assassination.

That report stated that the individual who ordered the assassination was Roberto D'Aubuisson, an army major and founder of El Salvador's right-wing ARENA party who died in 1992.

Pope Francis will declare Romero a saint on Oct. 14 in Rome, despite a Salvadoran request that the ceremony take place in the Central American country.