MINNEAPOLIS — The Archdiocese of St. Paul and Minneapolis made serious mistakes in the way it handled allegations of clergy sexual misconduct in the last decade, Archbishop John Nienstedt acknowledged Thursday as he announced he has ordered an external review of all priest files.

Nienstedt apologized to victims in a column posted on the website of The Catholic Spirit, the archdiocese’s official newspaper, and said he knows the ultimate responsibility lies with him as head of the local church.

“My heart is heavy with the agony that these errors have caused,” he wrote.

The archdiocese has come under fire since a former employee claimed church leaders mishandled abuse allegations. Nienstedt’s top deputy has stepped down, police are investigating, and there have been public calls for Nienstedt to resign.