Archbishop Carlo Maria Viganò’s bombshell “testimony” claiming that Pope Francis knew about allegations of Archbishop Theodore McCarrick’s sexual misconduct but still chose to make him a trusted adviser has placed the Holy See squarely in the spotlight of the widening Church crisis over the mishandling of clergy sexual abuse.

Archbishop Viganò’s testimony has been framed by some as an unwarranted act of aggression on a sitting pope. No doubt, the very public nature of Archbishop Viganò’s unsubstantiated allegations against Francis and other Vatican officials, whom he identifies by name and claims were complicit in suppressing accusations against McCarrick, is unprecedented in Church history.

Yet the author of the testimony is a retired senior Vatican official with detailed inside knowledge of Rome’s internal workings and an experienced diplomat who served as U.S. papal nuncio from 2011 to 2016.

Now, he has taken the irrevocable step of indicting an ecclesial culture that, until recently, accorded him enormous standing.

Thus far, Cardinal Daniel DiNardo, the president of the U.S. Conference of Catholic Bishops, along with more than 30 other bishops, has recognized that the charges leveled in the extraordinary letter of the former apostolic nuncio to the United States must be taken seriously and investigated promptly. “The questions raised deserve answers that are conclusive and based on evidence,” said Cardinal DiNardo. “Without those answers, innocent men may be tainted by false accusation and the guilty may be left to repeat sins of the past.”

In the wake of previous revelations that Archbishop McCarrick had been appointed the archbishop of Washington in 2000 and remained in his post for six years, despite repeated efforts by whistleblowers to alert Rome about allegations of his sexual misconduct involving seminarians and priests, the USCCB’s leadership had already committed to plans for an independent investigation. This work is expected to involve the collaboration of Vatican and U.S. Church leaders, with a prominent role for lay specialists. These preparations took on more urgency amid gruesome headlines prompted by the Pennsylvania grand jury report, which found that 300 priests had been accused of abusing 1,000 children in six dioceses over more than half a century and contended that the bishops in those dioceses at the time proceeded to cover it up.

Now, attention has centered on Archbishop Viganò’s assertion that Pope Francis knew in 2013 that Archbishop McCarrick faced allegations of sexual misconduct, yet lifted sanctions privately imposed by Pope Benedict XVI and granted him a key advisory role. The Pope has not yet offered a substantive response to the allegations. “I will not say a single word about this,” he said during an in-flight Aug. 26 news conference as he returned from the World Meeting of Families in Dublin, one day after Archbishop Viganò’s testimony was published. “I believe the statement speaks for itself. And you have the journalistic capacity to draw your own conclusions.”

The Holy Father’s reluctance to respond to the allegations could stem from a sure knowledge that they are substantially untrue, at least with respect to his own conduct, and a belief that journalistic investigation is the preferred way to establish this factually without violating the confidentiality of sensitive Vatican files.

But without an official investigation authorized by the Pope himself, it’s simply impossible to discredit the claims. Indeed, one key element — that Pope Benedict imposed some sort of restriction on Archbishop McCarrick because of the Vatican’s knowledge of his sexual misconduct with adult seminarians and priests — has been partially validated to the Register by a source close to the pope emeritus. At the same time, what the source described to the Register seemed to fall substantially short of the canonical “sanctions” that Archbishop Viganò insisted Benedict had mandated for the disgraced archbishop.

Archbishop Viganò’s fiercest media critics have latched onto this point of contention, along with other confusing or apparently contradictory aspects of his testimony, to cast doubt on both the integrity of the messenger and the claims embedded in his letter.

In addition, reporters have pointed to previous charges accusing the former nuncio of obstructing a 2014 investigation into allegations of sexual misconduct by Archbishop John Nienstedt of St. Paul and Minneapolis. Archbishop Viganò vehemently denied those charges subsequent to publication of his testimony, and Auxiliary Bishop Andrew Cozzens of St. Paul and Minneapolis, who was involved closely with the 2014 investigation, seems to have acknowledged Archbishop Viganò’s key points.

In reality, though, journalistic sleuthing can only go so far, at least in these special circumstances.

An official investigation is urgently needed in order to provide a comprehensive review of all the complicated facts in the story of Archbishop McCarrick’s rise and fall. The investigators must be charged with authority to review the Vatican and U.S. nunciature’s archives, where the critical documents validating these claims can be found, according to Archbishop Viganò. The investigators also must be given permission to interview every senior Church leader with knowledge of Archbishop McCarrick’s misconduct and Pope Benedict’s response to it.

The most contentious aspect of the former nuncio’s testimony — his assertion that the Pope should resign — is a much more complex matter. Many faithful Catholics are understandably dismayed that the question of a papal resignation has even been raised without clear substantiation of the accusations. Even if an investigation should substantiate the majority of the archbishop’s claims, Church history and tradition are not clear on what should happen next. What is most critical, at present, is for Pope Francis to move beyond his initial response to Archbishop Viganò’s testimony and offer a substantive message that matches the gravity of charges that have grieved the faithful.

On a practical level, the Pope’s decision to remain silent, combined with a series of “no comments” from Vatican authorities contacted by journalists, has constrained the work of reporters eager to vet Archbishop Viganò’s claims. Even the most resourceful journalistic investigation will fall short without access to relevant documents and critical witnesses. Cardinal DiNardo is right about the need for an evidence-based investigation. He has sought to meet immediately with Pope Francis in Rome to discuss this grave crisis. We pray that the meeting takes place, that the resolve of both the Holy Father and the U.S. bishops will be clear, and that a full investigation will be forthcoming.

Only with the Vatican’s cooperation will we see the documents that can prove or disprove Archbishop Viganò’s accusations. And only then will other Church authorities come forward and tell what they know.

Catholics, in the U.S. and in the universal Church, need to know the full truth. And until it is provided, the process of healing the wounds from the clerical crimes of the past and instituting the measures required to prevent their recurrence will be unacceptably impaired.