Well, in the novel, the D.A. draws the circle more times than in the movie. In the movie, he just does it once for the young woman. In the book, he does it a few times, even for the crooked lawyer.
In the book, the lawyer buys a house next door to where that family is living. When the cops and D.A. visit his home, they find a telescope there, and he says that he's into astronomy. Later they realize that he was just using the telescope to spy on the family (tee hee). In the movie, he was in the neighborhood, but not necessarily very close to the family.
It's been awhile since I read the book, but from what I remember, his involvement wasn't that different than what happened in the movie. I think that there was money in it for him or something like that. I admit that I didn't read over the financial details that carefully. I never do when I read mystery novels.
Jim Hutton: talented gorgeous hot hunk; adorable as ElleryQueen; SEXIEST ACTOR EVER