The name of the little girl who witnessed her parents' murder, Patricia Highsmith, is a reference to the suspense novelist of the same name, best known for such works as 'Strangers on a Train' and 'The Talented Mr. Ripley', among others.
One of the names in the log book, at the open house, was Travis Bickle. Travis Bickle was Robert Deniro's character in 'Taxi Driver'.