Detailed question for anyone who has seen & remembers "What Lies Beneath"?

this has been bugging me ever since i saw "what lies beneath" (harrison ford, michelle pfeiffer).... when claire finds the box in the lake with madison's necklace in it and confronts norman about him obviously having something to do with her death and he tells her what happened (or supposedly what happened), and she says "that girl must come up".. he takes the phone and calls the police saying he has info about a missing person and to send and officer out to the house.. he tells claire he's going upstairs to get dressed and that's where the movie turns and he tries to kill claire. SO, my question is, why is it that during all of what came after, with the bathtub scene and whatnot, why did the police never show up at the house? that never made sense to me. he gave his name and said madison frank's name, gave their address, etc.. so why was it not followed up on that he knew something about this case? and why did no one come to the house during the struggle between him & claire?