A monsignor who worked at the apostolic nunciature to the United States has corroborated an explosive report accusing Pope Francis of rehabilitating Cardinal Theodore McCarrick despite knowing of his record of homosexual abuse of priests and seminarians.

Contacted by the Catholic News Agency (CNA), Monsignor Jean-François Lantheaume, the former first counselor at the apostolic nunciature in Washington D.C., declined to give an interview, but affirmed the veracity of the report by Archbishop Carlo Maria Viganò.

“Viganò said the truth. That’s all,” he wrote to CNA.

In a written 11-page “testimony” published Saturday, the Vatican’s former ambassador to the United States said that Pope Francis had reinstating Cardinal Theodore McCarrick to a position of prominence despite direct knowledge of McCarrick’s sexual abuse.

Archbishop Viganò alleged that Pope Benedict XVI had imposed “canonical sanctions” on Cardinal McCarrick in 2009-2010 forbidding him from traveling, celebrating Mass in public, or participating in public meetings, but that Pope Francis later lifted these sanctions and made McCarrick a close personal advisor.

Now that “the corruption has reached the very top of the Church’s hierarchy,” he wrote, “my conscience dictates that I reveal those truths regarding the heart-breaking case of the Archbishop Emeritus of Washington, D.C., Theodore McCarrick, which I came to know in the course of [my] duties.”

In his testimony, Viganò makes reference to Monsignor Lantheaume as having told him of the “stormy” meeting between then-nuncio Archbishop Pietro Sambi and Cardinal McCarrick in which Sambi informed McCarrick of the sanctions that had been imposed by Pope Benedict.

“Monsignor Jean-François Lantheaume, then first Counsellor of the Nunciature in Washington and Chargé d’Affaires ad interim after the unexpected death of Nuncio Sambi in Baltimore, told me when I arrived in Washington — and he is ready to testify to it — about a stormy conversation, lasting over an hour, that Nuncio Sambi had with Cardinal McCarrick whom he had summoned to the Nunciature. Monsignor Lantheaume told me that ‘the Nuncio’s voice could be heard all the way out in the corridor.’”

Archbishop Viganò replaced Sambi as nuncio to the United States in 2011, at which time he claims to have been informed of the McCarrick situation by Lantheaume.

Lantheaume has now left the Vatican diplomatic corps and serves in priestly ministry in France, CNA reported.

In his testimony, Viganò stated that he personally informed the pope of McCarrick’s abuse on June 23, 2013 and yet Francis “continued to cover for him.”

“Holy Father, I don’t know if you know Cardinal McCarrick, but if you ask the Congregation for Bishops there is a dossier this thick about him,” Viganò claims to have told the pope. “He corrupted generations of seminarians and priests and Pope Benedict ordered him to withdraw to a life of prayer and penance.”

Viganò claimed that Pope Francis “did not take into account the sanctions that Pope Benedict had imposed on him and made him his trusted counselor along with Maradiaga,” the latter being Cardinal Oscar Rodriguez Maradiaga, the archbishop of Tegucigalpa, Honduras, who has been embroiled in scandals of both sexual and financial nature over the past months.

Follow Thomas D. Williams on Twitter Follow @tdwilliamsrome