An Italian nun killed 21 years ago ago by a group of teenage girls who were allegedly obsessed with devil-worship has been beatified by the Catholic Church as a martyr.

In a ceremony on Sunday that marks the last ritual step before someone is declared a saint, Pope Francis hailed Sister Maria Laura Mainetti, and described her killers as “prisoners of evil.” Mainetti had been lured to an alleyway in the town of Chiavenna by three teenage girls on June 6, 2000, and then bludgeoned and stabbed to death. Mainetti had originally been lured to the crime scene when one of the girls called her and asked her to meet her there, claiming she had been raped and was pregnant.

According to local reports, the teens had told investigators that Mainetti asked God to forgive them even as they ambushed her. The discovery of satan-related writings among the teens’ belongings had led investigators to believe that the killing had been satanically inspired. However, one girl would tell investigators they had murdered Mainetti “to do something different.” The attackers, who were all minors at the time of the murder, have since been released from prison.