clue to killer (massive spoilers!!!!!)

As cheesy and bad as the film is i've always thought it had a good whodunnit. And most people i know who have seen it don't guess it right but theres one scene which to me just gives it away and i'm suprised no one seems to pick up on it. When Patch goes to kevin's house for the first time. She is downstairs and suddenly we get treated to the killers pov shots from upstairs. Meaning the killer is upstairs and seconds later Kevin comes down the stairs so obvious conclusion is that kevin is the killer. But it obviously doesn't matter that much cos as i said everyone ive seen it with just doesnt notice that. Even the more eagle eyed of my friends