The Archdiocese of Philadelphia engaged in a long-standing criminal effort to protect sexual predator priests, putting the reputation of the church over the safety of children, prosecutors said Monday.

Assistant District Attorney Jacqueline Coelho told a jury during opening statements of a landmark trial against a priest and high-ranking church official that a decades-long conspiracy met victims with skepticism "at all cost."

Monday marked the beginning of prosecutors' case against Monsignor William Lynn and the Rev. James Brennan.

Lynn is the first U.S. church official charged in an administrative role with endangering children. Brennan is accused of raping a 14-year-old boy in 1996.

A defrocked priest who had been a co-defendant in the case pleaded guilty to sexual assault last week.