Next door to the pope's native Argentina, Chile has been roiled for years by a series of abuse cases, most notoriously that of Rev. Fernando Karadima, a charismatic priest whom the Vatican defrocked in 2011 for abusing teenagers during the 1980s and 1990s.
James Hamilton, a victim of Karadima, also expressed his disappointment during a press conference on Thursday. As recently as this week, Barros has denied witnessing any abuse.
'These people are truly insane, and the pontiff talks about atonement to the victims.
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.
Karadima's victims reported to church authorities as early as 2002 that he would kiss and fondle them in the swank Santiago parish he ran.
He said Cruz had testified in 2010 that Barros was present during the abuse.
The emeritus archbishop of Santiago subsequently apologised for having refused to believe the victims from the start.
"He declared himself innocent of the charges against him", Pope Francis told reporters, and he has appealed his cause to the Apostolic Signatura, the Vatican's supreme court.
His appointment outraged Chileans, badly divided the Osorno diocese and further undermined the church's already shaky credibility in the country.
Victims' groups have criticised the pope's record on abuse.
But he struck a defiant tone when asked about Barros by a Chilean journalist.
"The day they bring me proof against Bishop Barros, I will speak. It's all calumny. Is that clear?" But he also reaffirmed his support for Bishop Barros, saying he has not received any evidence against him.
But The Associated Press reported last week that the Vatican was so anxious about the fallout from the Karadima affair that it was prepared in 2014 to ask Barros and two other Karadima-trained bishops to resign and go on a yearlong sabbatical.
"United by hope we have been able to work together and highlight -with our presence- the great visit of Pope Francis, whom we love so much and who has lovingly shared his lessons with us", he concluded.
"It's incredible that the pope doesn't understand that the problem wasn't the word "proof" or 'evidence, ' which is the same thing, but that he accused victims of slander - victims who were found to be right by both Vatican and Chilean justice", he told the AP.
They staged an unprecedented protest during his 2015 installation ceremony and have protested his presence ever since.
"Why not do it today?" the pope said.
'He has just turned back the clock to the darkest days of this crisis, ' she said in a statement. It hurt a lot of abused people.
For years Catholic officials have accused victims of slandering and attacking the church with their claims.
"I must ask pardon [from them] because the word "proof" has hurt numerous abused, and [what] I meant to ask for was 'evidence.' I ask forgiveness".
Aboard the flight, the Pope also explained the background of letter he wrote to Barros two years ago, and which has recently surfaced.
The pope's comments have raised questions about his commitment to repairing the damage inflicted by the Church's sexual abuse scandals, and his determination to ensure no abuse is allowed to continue. Francis again said: "He remains there [in Osorno], I can not condemn him if I do not get the evidence".
"I realise that it is a slap in their faces, and now I realise that my expression was an unfortunate one".