By Tony Hanson

PHILADELPHIA (CBS) – While the unprecedented clergy abuse trial of former Monsignor William Lynn and two priests is set to begin Monday, the latest pre-trial hearing in the case makes clear the defendants won’t be the only ones on trial.

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Two priests — one now defrocked — allegedly abused children, and Monsignor William Lynn is charged with endangering children by allowing these and other alleged predator priests to remain in ministry.

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But, prosecutor Patrick Blessington said yesterday, they plan to present evidence showing there was “a diocese-wide policy that was criminal in nature.”

And the defense will attack the credibility of the accusers. Defense attorney Michael Wallace, who represents Edward Avery (now defrocked), has told the court the defense position is the incident alleged never happened. The allegations were fabricated by a troubled, drug abusing man who is out to make money and alleviate his own problems.

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All three defendants have pleaded not guilty.