The Norwegian director André Øvredal was inspired to do a horror movie after attending a screening of The Conjuring. He immediately called his agent and told them that they should try and find a good horror script for him. A month later they showed him this script and he was immediately interested.
The trivia item below may give away important plot points.
The director's favorite scene to film was the scene in the elevator when they discuss the death of the mother. He said "I only placed the camera, and we watched a fantastic performance by Brian Cox and Emile Hirsch". The scene he was most proud of as a director was the build up to the reveal of the symbols beneath Jane Does skin. As stated at the festival Monsters of Film in Stockholm 2016.