Aboard the papal plane from Lima to Rome Sunday, Pope Francis said that comments made to Chilean journalists Jan. 18 were not intended to cause pain for victims of clerical sexual abuse.

Francis said that he had meant to explain to Chileans that because he has not seen evidence that Chilean Bishop Juan Barros helped to cover up acts of sexual abuse, it would be unjust to condemn him.

The pontiff said that his use of "the word 'proof' was not the best in order to draw near to a suffering heart."

The Pope asked for forgiveness from victims he may have wounded, stating that unintentionally causing them harm "horrified" him, especially after he met with victims in Chile, as he has done on other trips, such as to Philadelphia in 2015.

"I know how much they suffer, to feel that the Pope says in their face 'bring me a letter, proof,' it's a slap," he said.

He also explained that he is aware that victims may not have brought forward evidence because it is unavailable, or because they are otherwise ashamed or afraid.

"Barros' case was studied, it was re-studied, and there is no evidence," Francis told journalists Jan. 21. "That is what I wanted to say. I have no evidence to condemn him. And if I condemn him without evidence or without moral certainty, I would commit the crime of a bad judge."

"If a person comes and gives me evidence," he continued, "I am the first to listen to him. We should be just."

Barros is accused by four victims of clerical sexual abuse of colluding to cover up the crimes of his longtime friend, Fr. Fernando Karadima. Francis has long defended Barros, who claims to be innocent. Barros has been a subject of controversy since his 2015 appointment to lead the Diocese of Osorno.

Karadima, who once led a lay movement from his parish in El Bosque, was convicted of sexually abusing minors in a 2011 Vatican trial, and at the age of 84, he was sentenced to a life of prayer and solitude.

During his Jan. 15-18 visit to Chile, Pope Francis met with abuse survivors, but when questioned about Barros by journalists on his last day in the country, he said, "the day they bring me proof against Bishop Barros, I'll speak. There is not one shred of proof against him. It's all calumny. Is that clear?"

The Pope's comment was met with fierce opposition, as critics said he was insensitive to abuse victims.

Cardinal Sean O'Malley, Archbishop of Boston and one of nine members of the Pope's Council of Cardinals, issued a statement Jan. 20 voicing criticism of the Pope's remarks.

"It is understandable that Pope Francis' statements yesterday in Santiago, Chile were a source of great pain for survivors of sexual abuse by clergy or any other perpetrator," O'Malley said.

"Words that convey the message 'if you cannot prove your claims then you will not be believed' abandon those who have suffered reprehensible criminal violations of their human dignity and relegate survivors to discredited exile," he said.

Since he was not personally involved in the Chilean cases, O'Malley said he couldn't speak as to why the Pope chose to use the specific words he did when responding to reporters.

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"What I do know, however, is that Pope Francis fully recognizes the egregious failures of the Church and its clergy who abused children and the devastating impact those crimes have had on survivors and their loved ones."

"Accompanying the Holy Father at numerous meetings with survivors I have witnessed his pain of knowing the depth and breadth of the wounds inflicted on those who were abused and that the process of recovery can take a lifetime," O'Malley said, adding that Francis' many statements insisting on a "zero-tolerance" policy for abuse in the Church "are genuine and they are his commitment."

During the press conference, the Pope said that he had seen O'Malley's statement and that he has appreciation for the cardinal: "I thank him for his statement because it was very just."

"[O'Malley] said all that I did and that I do, that the Church does, and then he spoke of the sorrow of victims" in general, Francis said. "Because many victims feel that they are not able to bring [forward] a document or a testimonial."

Aboard the flight, the Pope also explained the background of letter he wrote to Barros two years ago, and which has recently surfaced.

The letter illustrates a dialogue of 10-12 months between him and Barros, he said, beginning at the time the scandal concerning Karadima was revealed.

Francis said that at that time, someone from the Chilean bishops' conference suggested that the four bishops who had been close to Karadima should resign or take a sabbatical year until the scandal had passed over, "because they are good bishops."

At this time, Barros, who had been a bishop since 1995, followed this advice and submitted his resignation to the Holy See. Pope Francis said that he did not allow the bishop's resignation, because to do so would be "to admit culpability in advance," in his opinion. And in this case, as in any, "if there are culpable parties, it will be investigated."

In 2015, when Francis appointed Barros bishop of Osorno, Chile, there were protests, and again, Barros submitted his resignation, Francis said.

"I spoke with him for a long time, others spoke at length with him..." We all told him to continue as bishop, the Pope noted.

"They have continued to investigate Barros, but there is no evidence and this is what I wanted to say: I cannot condemn him because I don't have the evidence... But I am also convinced that he is innocent."

O'Malley is the head of the Pontifical Commission for the Protection of Minors, which just concluded a 3-year mandate in December. The Vatican has not issued any statements on the the commission since its expiration, causing some to speculate on the future of its existence.

In the most recent meetings of the Council of Cardinals, O'Malley spoke on the commission's continued work, explaining that it is in the Pope's hands to decide whether to reconfirm current members and whom to appoint as new members.

In the presser, Francis said that before the start of his trip, he had received a list of recommendations for new members, which he is now studying. The Pope did not say whether O'Malley would be reappointed.