The Vatican has opened a criminal trial against its former ambassador to the Dominican Republic and placed him under house arrest, marking the first time a high-ranking official has been criminally charged by the Vatican with sexual abuse of children.

Josef Wesolowski was defrocked in June after the Vatican’s canon law court found him guilty of abuse and returned him to life as a layman. Wesolowski, who is from Poland, had been recalled from his post in August 2013 amid allegations that he had sexually abused teenage boys.

What Pope Francis Has Done Differently in Tackling the Sexual Abuse Scandal

In a statement, Vatican spokesman Fr. Federico Lombardi, S.J. said that the move “is consistent with the wish expressed by the Pope that such a serious and delicate case be addressed without delay, with the just and necessary rigour, with the full assumption of responsibility on the part of the institutions governed by the Holy See.”

Because of health problems, Wesolowski is being held under house arrest in Vatican City, according to the statement.

In Secrets of the Vatican, FRONTLINE detailed the Vatican’s failure to address the church’s handling of abuse cases. Recent steps toward reform have included criminalizing sexual abuse and forming an advisory board.

But the pope has also defended the church’s handling of the crisis, telling an Italian newspaper in March that “no one else has done more.”

“The cases of abuse are awful because they leave profound wounds,” Francis said. But he added: “The Catholic Church is maybe the only institution to have moved with transparency and responsibility. No one else has done more. Yet the church is the only one to be attacked.”

You can watch Secrets of the Vatican here: