The Vatican said on Tuesday that it had placed under house arrest and opened criminal proceedings against one of its former ambassadors, Archbishop Jozef Wesolowski, who has been accused of sexually abusing boys he met on the street while serving in the Dominican Republic.
It is the first time the Vatican will hold a criminal trial on charges of child sexual abuse, and it comes as Pope Francis has been trying to set a new tone of rigorous attention in the long-running abuse scandal.
The case has received widespread attention in the Dominican Republic and in Mr. Wesolowski’s native Poland, and officials in both nations have sought to have him tried in their courts.
Mr. Wesolowski is being held “in a location within the Vatican City State,” according to a statement issued by the Rev. Federico Lombardi, the Vatican spokesman. He added that Mr. Wesolowski had presented documentation attesting to a medical condition, and was confined to house arrest after a preliminary hearing on Tuesday.
The tiny Vatican city-state has no jail facility for holding prisoners on a long-term basis. The Italian newspaper La Repubblica reported that Mr. Wesolowski had been living in a convent. A bishop from the Dominican Republic said he had spotted the former ambassador strolling along a street in Rome in June.
That was the same month that Mr. Wesolowski, who is 66 and a citizen of both the Holy See and Poland, was defrocked in a canonical church proceeding. He is appealing that decision.
Father Lombardi said the arrest and trial of Mr. Wesolowski were “a result of the express desire of the pope, so that a case so serious and delicate would be addressed without delay, with just and necessary rigor.”
The former Vatican diplomat was secretly recalled from Santo Domingo, the Dominican capital, in August 2012 after church officials in the Dominican Republic learned of allegations that Mr. Wesolowski had been picking up young shoeshine boys on the waterfront and paying them for sexual acts. The allegations came in a letter to church officials from a local deacon who was arrested while, he wrote, he was trying to procure child victims for Mr. Wesolowski.
The authorities in the Dominican Republic did not learn of the allegations until Mr. Wesolowski had left the country. The district attorney in Santo Domingo, Yeni Berenice Reynoso Gómez, said her investigators had identified at least four victims. She said it was “the most terrible case I have ever seen” because the ambassador was accused of bribing poor children for sex, offering money and, in one case, medicine to treat a child’s epilepsy.
The Vatican claimed diplomatic immunity for Mr. Wesolowski until last month, one day after The New York Times reported on the case. A spokesman for the district attorney said in an interview this month that the Dominican authorities were requesting information from the Vatican about how the extradition of Mr. Wesolowski would proceed, but that the Vatican had not yet responded.
Elisabetta Povoledo contributed reporting from Milan, and Ezra Fieser from Santo Domingo, Dominican Republic.