Why did he take the case?
I suspect because of the previous case with the boy and the same Priest who he was forced to sweep under the rug.
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Scientologists love Narnia, there's plenty of closet space.
Correct - and that only comes out at the end as we are shown up front he is just a publicity hound, and he makes no protest re that.
then there is bar scene and "bad bad thing"
we also see the Inspector bloke with bad cold go and check the videos to make sure they have not been touched, ie he knew all about the holy man from the previous O'Donnell matter.
what is not clear is how Roy actually knew about O'Donnell from 10 years ago [was he also abused?] which caused him to seek revenge and fabricate Aaron to do so.
he was very smart about people and law and KNEW Marty would get his case
http://www.kindleflippages.com/ablog/