During the autopsy Ducky tells Jimmy and Tony that Norman Bates (Psycho) is based on the serial killer Ed Gein, Gein is also the inspiration for Hannibal Lecter (Silence of the Lambs), Buffalo Bill (Silence of the Lambs) and Leather Face (Texas Chainsaw Massacre).
Also the large house was used in Dagger of the Mind (1972) made in the 1970's. It was supposed to be an English house in the UK.
At 40:53- after Barrett dons the bath towel you can see she has two scars above her left breast; seemingly from bullet wounds.