As archbishop, Romero spoke out against social injustice and violence amid the escalating conflict between the military government and left-wing insurgents that led to the Salvadoran Civil War.

Though no one was ever convicted for the crime, investigations by the UN-created Truth Commission for El Salvador concluded that Major Roberto D'Aubuisson, a death squad leader and later founder of the right-wing Nationalist Republican Alliance (ARENA) political party, had ordered the killing.

[5] In 1997, Pope John Paul II bestowed upon Romero the title of Servant of God, and a cause for his beatification was opened by the church.

Seen as a social conservative at the time of his appointment as archbishop in 1977, Romero was deeply affected by the murder of his friend and fellow priest Rutilio Grande and thereafter became an outspoken critic of the military government of El Salvador.

He left the seminary for three months to return home when his mother became ill after the birth of her eighth child; during this time he worked with two of his brothers in a gold mine near Ciudad Barrios.

He completed his studies at the Gregorian University in Rome, where he received a Licentiate in Theology cum laude in 1941, but had to wait a year to be ordained because he was younger than the required age.

On the route home, they made stops in Spain and Cuba, where they were detained by the Cuban police, likely for having come from Fascist Italy,[22] and were placed in a series of internment camps.

His death had a profound impact on Romero, who later stated: "When I looked at Rutilio lying there dead I thought, 'If they have killed him for doing what he did, then I too have to walk the same path.

In response to Grande's murder, Romero revealed an activism that had not been evident earlier, speaking out against poverty, social injustice, assassinations and torture.

[34] On 11 May 1979, Romero met with Pope John Paul II and unsuccessfully attempted to obtain a Vatican condemnation of the Salvadoran military regime for committing human rights violations and its support of death squads, and expressed his frustration in working with clergy who cooperated with the government.

Romero denounced the persecution of members of the Catholic Church who had worked on behalf of the poor:[37] In less than three years, more than fifty priests have been attacked, threatened, calumniated.

"[48][49] On 23 March 1980, Archbishop Romero delivered a sermon in which he called on Salvadoran soldiers, as Christians, to obey God's higher order and to stop carrying out the government's repression and violations of basic human rights.

[51][21] Romero spent 24 March in a recollection organized by Opus Dei,[8] a monthly gathering of priest friends led by Fernando Sáenz Lacalle.

"[58] At the funeral, Cardinal Ernesto Corripio y Ahumada, speaking as the personal delegate of Pope John Paul II, eulogized Romero as a "beloved, peacemaking man of God," and stated that "his blood will give fruit to brotherhood, love and peace.

"[59] During the ceremony, smoke bombs exploded on the streets near the cathedral and subsequently, there were rifle shots that came from surrounding buildings, including the National Palace.

[60] Some witnesses claimed it was government security forces who threw bombs into the crowd, and army sharpshooters, dressed as civilians, who fired into the chaos from the balcony or roof of the National Palace.

[70] On 25 March 1980, US Secretary of State Cyrus Vance revealed that the White House would continue to fund the Salvadoran government and provide it military aid, in spite of the pleas of Romero and his death immediately prior to this announcement.

The 12,000 documents revealed that the administrations of Ronald Reagan and George H. W. Bush knew of the assassinations conducted by D'Aubuisson, including that of Romero, yet still worked with him despite this.

[60] D'Aubuisson had strong connections to the Nicaraguan National Guard and to its offshoot the Fifteenth of September Legion[77] and had also planned to overthrow the government in a coup.

Álvaro Rafael Saravia, a former captain in the Salvadoran Air Force, was chief of security for D'Aubuisson and an active member of these death squads.

Speaking before Romero's family, representatives of the Catholic Church, diplomats, and government officials, Funes said those involved in the assassination "unfortunately acted with the protection, collaboration, or participation of state agents.

"[80] A 2000 article by Tom Gibb, then a correspondent with The Guardian and later with the BBC, attributes the murder to a detective of the Salvadoran National Police named Óscar Pérez Linares, acting on the orders of D'Aubuisson.

The article cites an anonymous former death squad member who claimed he had been assigned to guard a house in San Salvador used by a unit of three counter-guerrilla operatives directed by D'Aubuisson.

[83] In April 2017, however, in the wake of the overruling of a civil war amnesty law the previous year, a judge in El Salvador, Rigoberto Chicas, allowed the case against the escaped Saravia's alleged role in the murder of Romero to be reopened.

On 23 October 2018, days after Romero's canonization, Judge Chicas issued a new arrest warrant for him, and Interpol and the National Police are charged with finding his hideout and apprehending him.

"[98] In March 2005, Vincenzo Paglia, the Vatican official in charge of the process, announced that Romero's cause had cleared a theological audit by the Congregation for the Doctrine of the Faith, at the time headed by Cardinal Joseph Ratzinger (later elected Pope Benedict XVI) and that beatification could follow within six months.

"[100] In an October 2005 interview, Cardinal José Saraiva Martins, the Prefect of the Congregation for the Causes of Saints, was asked if Paglia's predictions of a clearance for Romero's beatification remained on track.

"[102] Although Benedict XVI had always been a fierce critic of liberation theology, Paglia reported in December 2012 that the Pope had informed him of the decision to "unblock" the cause and allow it to move forward.

[109] Archbishop Vincenzo Paglia, the postulator (chief promoter) of the causes of saints, said that Romero's assassination at the altar was intended "to strike the Church that flowed from the Second Vatican Council" and that the motive for his murder "was not caused by motives that were simply political, but by hatred for a faith that, imbued with charity, would not be silent in the face of the injustices that relentlessly and cruelly slaughtered the poor and their defenders.

Amato presided over the ceremony on behalf of Francis, who in a letter to the Archbishop of San Salvador José Luis Escobar Alas marked the occasion by calling Romero "a voice that continues to resonate.