A searing report published Wednesday by Illinois Attorney General Lisa Madigan claims the Roman Catholic Church withheld more than 500 names of clergy accused of sexually abusing minors.

The report contains what Madigan called the “preliminary” findings of an investigation her office launched in August, prompted by a Pennsylvania grand jury’s revelations that six Roman Catholic dioceses in the state had covered up sexual abuse by 301 “predator priests” over 70 years.

Madigan’s investigation also looked at six Illinois dioceses ― the Archdiocese of Chicago, and the dioceses of Belleville, Joliet, Peoria, Rockford and Springfield.

She found that, though the dioceses had publicly identified 185 clergy members who had been “credibly” accused of child sexual abuse, there are more than 500 others whose names were withheld and who were not investigated.

The six dioceses have, in total, received allegations of sexual abuse against about 690 clergy, Madigan’s report found.

“By choosing not to thoroughly investigate allegations, the Catholic Church has failed in its moral obligation to provide survivors, parishioners and the public a complete and accurate accounting of all sexually inappropriate behavior involving priests in Illinois,” Madigan said in a statement. “The failure to investigate also means that the Catholic Church has never made an effort to determine whether the conduct of the accused priests was ignored or covered up by superiors.”

Madigan’s office also said church leaders often failed to notify law enforcement authorities or Department of Children and Family Services (DCFS) about the allegations, sometimes citing that the clergy member had died or resigned by the time the allegation was made.

Though Madigan said the investigation is ongoing, one of her key takeaways thus far was that “the Catholic Church cannot police itself.”

“Allegations of sexual abuse of minors, even if they stem from conduct that occurred many years ago, cannot be treated as internal personnel matters,” Madigan said.

The Archdiocese of Chicago released a lengthy statement responding to Madigan’s report, detailing its efforts to respond to allegations against clergy members and support victims of abuse.

Max Rossi / Reuters Cardinal Blase J. Cupich, archbishop of Chicago, said, “It is the courage of victim-survivors that has shed purifying light on this dark chapter in church history.”

“We investigate every allegation against an archdiocesan priest we receive, regardless of whether the accused is alive or dead,” the archdiocese said, in an apparent contradiction of Madigan’s findings. “When we learn of an allegation of abuse we act promptly, report it to civil authorities, remove the accused from ministry and investigate the allegation.”

Cardinal Blase J. Cupich, archbishop of Chicago, acknowledged in a statement the Catholic Church’s “failures to address the scourge of clerical sexual abuse.”

“It is the courage of victim-survivors that has shed purifying light on this dark chapter in church history,” he said.