Landmark Priest-Abuse Trial Begins In Philly [VIDEO]

Defense lawyers plan to attack the credibility of the troubled adult accusers when two Roman Catholic priests go on trial in a landmark child sex-abuse case.

But that strategy took a hit Thursday when a co-defendant entered a last-minute guilty plea. Defrocked priest Edward Avery's plea confirms one accuser's account of a brutal 1999 sexual assault inside a church sacristy.

The plea leaves Monsignor William Lynn and the Rev. James Brennan on trial on Monday.

The 61-year-old Lynn is the first U.S. church official ever charged with endangering children for allegedly failing to oust Avery and Brennan from ministry despite prior child-sex complaints.

The 48-year-old Brennan is charged with raping a 14-year-old boy in 1996.

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