Plz help whats the name of this film?

About a young girl babysitting some kids than this guy starts ringing her up saying have u checked the children then he starts knocking on her door when she answers it there's no1 there towards middle of film the children die years later she lives alone then she notices things have moved in house she sees shrink than a private investigater investigates what's going on then toward the end of film he than disguises himself painted into the wall detective tells her to shoot at fireplace as she shoots he comes out of fireplace can u tell me the name of this film thanx