The letter was graphic not just in describing how the priest kissed and fondled the boy, but also in how other priests who saw the abuse tried to hush it up. Pope Francis said recently that none of the victims had come forward to denounce the coverup, so the news that the letter was hand-delivered to Francis in 2015 is adding fuel to one of the biggest scandals of his five-year papacy.
The Associated Press obtained the eight-page letter, written in Francis' native Spanish, and was told by both the victim who wrote it and by members of the Pope's sex-abuse commission that Francis' top adviser assured them he gave it to the Pope.
The Pope's trip to Chile last month was marred by protests over his vigorous defence of Bishop Juan Barros, who is accused by victims of witnessing and ignoring the abuse of young parishioners by the Reverend Fernando Karadima. During the trip, Francis dismissed accusations against Barros as "slander", seemingly unaware that victims had placed him at the scene of Karadima's crimes.
On the plane home, confronted by an AP reporter, the Pope said: "You, in all good will, tell me that there are victims, but I haven't seen any, because they haven't come forward."
But members of the Pope's Commission for the Protection of Minors say that in April 2015, they sent a delegation to Rome specifically to hand-deliver the letter from Juan Carlos Cruz because they were alarmed by Francis' recent appointment of Barros as a diocesan bishop.
Cruz's account of the abuse he suffered at Karadima's hands had helped Vatican investigators decide to remove him from ministry and sentence him in 2011 to a lifetime of "penance and prayer". Barros was a Karadima protege, and according to Cruz and other victims, he witnessed the abuse and did nothing.
"Holy Father, it's bad enough that we suffered such tremendous pain and anguish from the sexual and psychological abuse, but the terrible mistreatment we received from our pastors is almost worse," Cruz wrote to the Pope.
On April 12, 2015, the members of the sex-abuse commission met with Francis' top adviser, Cardinal Sean O'Malley, explained their objections to Barros' appointment as Bishop of Osorno, and gave him the letter to deliver to the Pope.
"He assured us he would give it to the Pope and speak of the concerns," then-commission member MarieCollins told the AP. "And at a later date, he assured us that that had been done."
Cruz, who now lives in Philadelphia, heard the same. "Cardinal O'Malley called me after the Pope's visit here in Philadelphia and he told me, among other things, that he had given the letter to the Pope - in his hands," he said on Monday.
Neither the Vatican nor O'Malley responded to multiple requests for comment.
After Francis' comments backing Barros caused such an outcry in Chile, he was forced last week to do an about-face: The Vatican announced it was sending in its most respected sex-crimes investigator to take testimony about Barros from Cruz and others.
In the letter to the Pope, Cruz described how Karadima would kiss Barros and fondle his genitals, and do the same with younger priests and teens.
"More difficult and tough was when we were in Karadima's room and Juan Barros - if he wasn't kissing Karadima - would watch when Karadima would touch us - the minors - and make us kiss him, saying: 'Put your mouth near mine and stick out your tongue'. He would stick his out and kiss us with his tongue," Cruz wrote. "Juan Barros was a witness to all this innumerable times, not just with me but with others as well."
Barros has repeatedly denied witnessing any abuse or covering it up. "I never knew anything about, nor ever imagined, the serious abuses which that priest committed against the victims," he told the AP recently. "I have never approved of nor participated in such serious, dishonest acts, and I have never been convicted by any tribunal of such things."
But that's hardly the question Barros' opponents are asking - Barros was a young priest and had no authority over Karadima when the abuse was occurring. Instead, many question how a prelate who didn't recognise a priest's abuse of young boys can run a diocese where he is responsible for protecting children from paedophiles.
How it unfolded
• Jan 10, 2015 Pope names Barros, then Chile's military chaplain, as Bishop of Osorno, over the objections of some members of the Chilean bishops' conference. They were concerned about the fallout from the Karadima affair.
• Jan 31, 2015 Francis acknowledged the bishops' concerns in a letter, which the AP obtained last month. The letter revealed a plan to have Barros and two other Karadima-trained bishops resign and take yearlong sabbaticals, but Francis wrote that it fell apart because the nuncio revealed it. The Pope later acknowledged that he had blocked the plan himself because there was no "evidence" Barros was guilty of any cover-up.
• Feb 2015 Fifty Chilean lawmakers and priests, deacons and more than 1000 laity in the Osorno diocese sign petitions protesting Barros' appointment and urging Francis revoke it.
• Feb 3, 2015 Juan Carlos Cruz writes an eight-page letter to the Vatican's ambassador in Santiago, Monsignor Ivo Scapolo, accusing Barros of watching the sex abuse he experienced and doing nothing to stop it.
• March 21, 2015 The Mass installing Barros as bishop of Osorno is marred by violent protests. Black-clad demonstrators storm the church with signs that read, "No to Karadima's accomplice." Ten days later, the Vatican publicly defends Barros, saying it "carefully examined the prelate's candidature and did not find objective reasons to preclude the appointment".
• April 12, 2015 Four members of the Pope's Pontifical Commission for the Protection of Minors fly to Rome to meet with Cardinal Sean O'Malley, Francis' top adviser, to raise concerns about Barros' suitability to run a diocese. The commissioners cite the victim testimony that Barros witnessed and ignored abuse. Member Marie Collins hands Cruz's letter to O'Malley, who would go on to tell Collins and Cruz he delivered it to the Pope and relayed their concerns.
• May 15, 2015 Pope is filmed in St Peter's Square telling the spokesman for the Chilean bishops' conference that the Chilean church had become too politicised and the opposition to Barros was coming from "leftists". Francis says: "Osorno suffers, yes, from foolishness, because they don't open their heart to what God says and they let themselves guided by the nonsense all those people say."
• Jan. 15, 2018 Francis arrives in Chile to protests that are unprecedented for a papal visit. During his first public remarks, he apologises for the "irreparable damage" suffered by all victims of sexual abuse. He meets with two survivors and weeps with them.
• Jan 18, 2018 While visiting the northern city of Iquique, Francis is asked by a Chilean journalist about Barros and says: "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?"
• Jan 20, 2018 Cardinal O'Malley publicly rebukes the Pope, saying his words in Iquique "were a source of great pain" for abuse survivors. "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," O'Malley said.
• Jan 21, 2018 Francis partially apologises, saying he shouldn't have used the word "proof" but rather "evidence". During an inflight news conference, he repeats that accusations against Barros are "slander" and denies any victims had come forward accusing Barros of covering up for Karadima. "I'm convinced he's innocent."
• Feb 6, 2018 The AP reports the contents of Cruz's letter, which contradict the Pope's claim about no victims coming forward. Cruz wrote: "Holy Father, it's bad enough that we suffered such tremendous pain and anguish from the sexual and psychological abuse, but the terrible mistreatment we received from our pastors is almost worse."