In the movie, "One hour photo", Sy takes many pictures of a little girl and gets them developed at his own shop. Like the police officer observed, Sy knew they'd get to Bill and he'll set the Police after him. Which did happen, and was directly the reason he was tracked down and arrested.
Unlike the officer's suspicion, it doesn't seem like it was a part of a bigger master plan at all! If he hadn't done that bit, he could have gone free after traumatising Maya and Will. What purpose did Sy think it might serve?