Pope Francis has started making good on his promise to not let even the most senior churchmen get away with sex abuse or cover-up.

On Monday, he accepted the resignation of the embattled archbishop of St. Paul and Minneapolis and his deputy bishop after prosecutors there charged the archdiocese with having failed to protect children from unspeakable harm from a pedophile priest who was later convicted of molesting two boys.

Separately, the Vatican indicted its own former ambassador to the Dominican Republic with sexually abusing minors in the Caribbean country -- the highest-ranking Vatican official ever to stand trial for a sex crime.

The developments came days after Francis approved the creation of a new tribunal inside the Vatican to specifically hear cases of bishops accused of failing to protect minors, answering years of criticism that top-ranked churchmen have long been immune to punishment for ignoring or covering up for priests who rape and molest children.

It's not clear if the tribunal -- once it becomes functioning -- would handle the case of Archbishop John Nienstedt and Auxiliary Bishop Lee Anthony Piche of St. Paul and Minneapolis, since they are now no longer in office.

They quit under the code of canon law that allows bishops to resign before they retire because of illness or some other "grave" reason that makes them unfit for office.

Earlier this month, prosecutors charged the Archdiocese of St. Paul and Minneapolis as a corporation of having "turned a blind eye" to repeated reports of inappropriate behavior by a priest who was later convicted of molesting two boys. No individual was named in the complaint.

The charges came two years after diocesan canon lawyer-turned-whistleblower Jennifer Haselberger alleged widespread cover-up of clergy sex misconduct in the archdiocese, saying archbishops and their top staff lied to the public and ignored the U.S. bishops' pledge to have no tolerance of priests who abuse.

Haselberger, who was Nienstedt's archivist, accused the church of using a chaotic system of record-keeping that helped conceal the backgrounds of guilty priests who remained on assignment.

She said she repeatedly warned Nienstedt and his aides about the risk of keeping accused priests in ministry, but they took action only in one case. As a result of raising alarms, she said she was eventually shut out of meetings about priest misconduct, and later resigned.

Nienstedt had refused to resign after Haselberger's accusations, and later after announcing that allegations had been made against him of inappropriate sexual behavior. He denied misconduct and the archdiocese hired a firm to investigate. No results were ever announced and recently Nienstedt hired his own attorney to look at the matter again.

In a statement Monday, Nienstedt said he was stepping down to give the archdiocese a new beginning. But he insisted he was leaving "with a clear conscience knowing that my team and I have put in place solid protocols to ensure the protection of minors and vulnerable adults."

In a statement, Piche said: "The people of the Archdiocese of Saint Paul and Minneapolis need healing and hope. I was getting in the way of that, and so I had to resign."

With Monday's resignations, there have been 18 bishops who have resigned after being publicly criticized for covering up for abusers, according to Anne Barrett Doyle of the online resource BishopAccountability.org.

In April, Francis accepted the resignation of U.S. bishop Robert Finn, who had been convicted in a U.S. court of failing to report a suspected child abuser.

Francis has pledged that not even high-ranking churchmen -- "daddy's boys" he called them -- will get away with abuse or cover-up.

"All bishops must carry out their pastoral ministry with utmost care in order to help foster the protection of minors, and they will be held accountable," Francis declared in July during a Mass with survivors of abuse at the Vatican.

The criminal charges against the archdiocese stem from its handling of Curtis Wehmeyer, a former priest at Church of the Blessed Sacrament in St. Paul, who is serving a five-year prison sentence for molesting two boys and faces prosecution involving a third boy in Wisconsin.

Prosecutors say church leaders failed to respond to "numerous and repeated reports of troubling conduct" by Wehmeyer from the time he entered seminary until he was removed from the priesthood in 2015. The criminal complaint says many people -- including parishioners, fellow priests and parish staff -- reported issues with Wehmeyer, and many of those claims were discounted.

The resignations came on the same day that the Vatican announced it was putting its former ambassador to the Dominican Republic, Jozef Wesolowski, on trial in a Vatican court on charges he sexually abused boys in the Caribbean country and possessed child pornography. Wesolowski, who has already been defrocked after being convicted in a canon law court, now faces possible jail time if convicted by the criminal tribunal of the Vatican City State.

The case has been highly sensitive, given that the Polish-born Wesolowski was an ambassador of the Holy See -- a direct representative of the pope and not just one of the world's 440,000 priests -- and had been ordained both a priest and a bishop by St. John Paul II.