As Pope Benedict XVI has come under scrutiny for his handling of sexual abuse cases, both his supporters and his critics have paid fresh attention to the way he responded to a sexual abuse scandal in Austria in the 1990s, one of the most damaging to confront the church in Europe.

Defenders of Benedict cite his role in dealing with Cardinal Hans Hermann Groër of Vienna as evidence that he moved assertively, if quietly, against abusers. They point to the fact that Cardinal Groër left office six months after accusations against him of molesting boys first appeared in the Austrian news media in 1995. The future pope, they say, favored a full canonical investigation, only to be blocked by other ranking officials in the Vatican.

A detailed look at the rise and fall of the clergyman, who died in 2003, and the involvement of Benedict, a Bavarian theologian with many connections to German-speaking Austria, paints a more complex picture.

Benedict, then Cardinal Joseph Ratzinger, had the ear of Pope John Paul II and was able to block a favored candidate for archbishop of Vienna, clearing the way for Father Groër to assume the post in 1986, say senior church officials and priests with knowledge of the process. His critics question how this influence failed him nine years later in seeking a fuller investigation into the case.

Benedict’s ambiguous role has made the Groër case a kind of Rorschach test of the future pope’s treatment of sexual abuse during his long stewardship of the Congregation of the Doctrine of the Faith, the Vatican’s powerful doctrinal body.

There are indications that Benedict had a lower tolerance for sexual misconduct by elite clergy members than other top Vatican officials....