A U.S.-based Roman Catholic Church official convicted of hiding child sex abuse by priests was sentenced Tuesday to a prison term of up to six years.

Monsignor William Lynn, who oversaw the work of 800 priests in the Archdiocese of Philadelphia, was in charge of investigating sex abuse claims against priests from 1992 to 2004. But a judge Tuesday said Lynn, instead, “enabled monsters in clerical garb.”

Lynn is the first senior U.S. church official convicted of covering up sex abuse claims, in a far-reaching scandal that has rocked the Catholic Church for more than a decade.

During his trial last month, prosecutors said that in one case, the 61-year-old defendant dealt with sex abuse claims by transferring a predatory priest to an unsuspecting parish.

Lynn's lawyers argued that their client followed established procedures. They said they will appeal.

Lynn's conviction was based on evidence that he recommended in the 1990s the transfer of suspect priest Edward Avery, allowing him to live near a Philadelphia church school. The transfer order came despite evidence of Avery's sexual misconduct with a child several years earlier.

Avery went on to assault another child in 1999. He was later defrocked, and is currently serving a 30- to 60-month prison sentence after pleading guilty to abuse charges earlier this year.