Here she dreamcasts an adaptation of the book:
First of all, I have to say I am writing a screenplay on The Boy Who Shot the Sheriff, so, of course, casting does come to mind from time to time.Learn more about the book and author at Nancy Bartley's website, and follow her on Twitter.
Since the lead would require a very strong child actor who move from 12 to 21, it's a big challenge. Asa Butterfield, The Boy in the Striped Pajamas, would be my pick. He can move an audience to tears without over playing the part. The Niccolls role calls for someone who can be vulnerable and willing to please, yet at the same time has a side quite capable to lying, cheating and even killing.
The wonderful Tom Hanks would be my pick for the warden, who turns around the life of the 12-year-old killer. Warden McCauley is a complex man. On one hand, he is known as the liberal warden because he believes in all kinds of prison reforms but on the other, he is still tough and presides over executions. The 1930s was the bloodiest time in the nation's penitentiaries with more people being put to death than at any other time.
There are smaller parts -- Walter Du Buc, the 17-year-old who is executed, I'd use Liam James, the Canadian up-and-coming actor, who does serious and sulky so well. Armene Lamson, the child-welfare crusader, I'd use Meryl Streep (who wouldn't?). No one, could do better when it comes to playing a driven woman who takes on a governor to free a child murderer.