PARIS (AP) — French police are investigating an allegation that the former archbishop of Paris sexually assaulted a woman who is under legal protection as a vulnerable person, prosecutors said Wednesday.

Michel Aupetit, who unexpectedly resigned in December 2021 after admitting to an “ambiguous” relationship with a woman in 2012, denies any wrongdoing, his lawyer said.

The police investigation of Aupetit was opened on the basis of information from the Paris archdiocese, the Paris prosecutors’ office said, confirming French media reports.

It was launched in late November 2022, on a preliminary potential charge of sexual assault on a vulnerable person, the prosecutors’ office said. The alleged assault took place several years ago, it added, providing no other details.

Aupetit’s lawyer, Jean Reinhart, said the probe was triggered by a letter sent to the Paris archdiocese. The diocese then forwarded the letter to prosecutors, an automatic procedure for handling potential abuse cases that Aupetit himself put in place when he was archbishop, Reinhart said. Prosecutors then launched the police probe.

Reinhart said Aupetit has not seen the letter, hasn’t been told who wrote it or what specifically it contains.

“My client is flabbergasted, doesn’t know what this is about,” the lawyer said.