(RNS) — As everyone not living in a total news blackout knows by now, the former papal nuncio to the United States, Archbishop Carlo Maria Viganò, has issued a call for Pope Francis to resign his office, on the grounds that the pontiff knew (because Viganò says he told him) about the sexual sins of Cardinal Theodore McCarrick and did nothing about it (until he did).

The call came in the form of a long letter accusing an array of high-ranking prelates (mostly but not exclusively progressives associated with Francis) of protecting clerical abusers and covering up evidence of their wrongdoing.

Viganò is a well-known traditionalist ideologue and Francis critic, but that in itself is not sufficient reason for calling his credibility into question.

Sufficient reason would be if in 2014 Viganò himself, as nuncio, put a stop to the investigation of the then-archbishop of St. Paul and Minneapolis, John Nienstedt, who had been credibly accused of sexual abuse. On Sunday, Viganò issued a statement denying that he did anything of the sort.

The basis for the charge against him is a July 7, 2014 memorandum on the Nienstedt investigation written by Dan Griffith, a priest and lawyer who managed the investigation as the archdiocese’s delegate for a safe environment. The 11-page, single-spaced document was sent to the archdiocese’s two auxiliary bishops — Lee A. Piché, who had overall responsibility for the investigation, and Andrew Cozzens — shortly after the two lawyers hired to investigate Nienstedt’s behavior tendered their resignations.

Griffith, profoundly upset, tells the story of how the investigation was shut down. Briefly, the lawyers had come up with a large amount of compelling evidence that Nienstedt had been abusing seminarians and engaging in flamboyant sexual activity for many years. The two auxiliary bishops and other clergy involved in the investigation reached a consensus that Nienstedt would have to resign.

Piché and Cozzens then flew to Washington with Nienstedt to meet with the nuncio to reach a “pastoral resolution”; i.e. a smooth resignation. Although they called Griffith after the meeting to say that such a resolution was in the offing, a subsequent one-on-one between Nienstedt and Viganò led to the nuncio’s telling the bishops that he didn’t think the allegations were that serious, and that the investigation should be halted.

Archbishop Carlo Maria Viganò listens to remarks at the United States Conference of Catholic Bishops’ annual fall meeting on Nov. 16, 2015, in Baltimore. (AP Photo/Patrick Semansky)

The bishops immediately responded by writing Viganò a letter in which they “disagreed with his decision to shut down the investigation, noting that this would rightly be seen as a cover-up.” The nuncio, in response, told the bishops to get rid of their letter. Indeed, he admitted doing so in his statement on Sunday:

I did instruct one of the auxiliary bishops, Lee A. Piché, to remove from the computer and the archdiocesan archives the letter falsely asserting that I had suggested the investigation be halted. I insisted on this not only to protect my name, but also that of the Nunciature and the Holy Father who would be unnecessarily harmed by having a false statement used against the Church.

If you believe that this was about anything more than Viganò protecting himself from criticism, then you have to believe that Piché and Cozzens not only misunderstood Viganò but also, after receiving the instruction to correct the misunderstanding, shut down the investigation anyway, thereby leading to the resignation of the lawyers.

This is, quite simply, incredible.

The fact of the matter is that the investigation had proved beyond question that Nienstedt was guilty of abuse and sexual misconduct. Take a look at the evidence in the dossier of affidavits Viganò was presented with, and that ultimately did lead to Nienstedt’s resignation.

Viganò, by the way, also says in his statement that, a year and a half ago, he asked the current nuncio, Christophe Pierre, and also the archbishop of St. Paul and Minneapolis, Bernard Hebda, to make public corrections to the Griffith memo, but that “(i)n spite of repeated emails and phone calls, I never heard back from them.”

Over at the American Conservative, Rod Dreher finds Viganò “credible.” LifeSite News finds Griffith’s actions to be “suspect.” I say it’s time to investigate exactly what happened.

Cozzens remains at his post in the Archdiocese of St. Paul and Minneapolis while Piché retired in 2015; perhaps one retains the letter they wrote protesting what they understood to be Viganò’s decision. Griffith pastors Our Lady of Lourdes Catholic Church in Minneapolis and serves as a faculty fellow and chaplain at the Terrence J. Murphy Institute for Catholic Thought, Law, and Public Policy at the University of St. Thomas in Minneapolis. The investigation shouldn’t take long.

In the meantime, it’s worth quoting from the conclusion of Griffith’s impassioned memo:

In one of my recent meetings with Bishop Cozzens I told him that his generation of bishops must work hard to hold their brother bishops accountable. This is an area that needs serious reform throughout the Catholic Church. There is an ugly clericalism on full display in this present matter, the type of which Pope Francis is trying to purge from the Church. Our bishops must be held accountable for their decisions, their behavior, and their performance. Our Catholic faithful deserve better and will demand better in the coming years.

Those years have arrived.

(Mark Silk writes the Spiritual Politics column for RNS. The views expressed in this commentary do not necessarily reflect those of Religion News Service.)