According...
Nicholas Constantine, who co-wrote the adapted screenplay, confirmed Franco's collaboration: "I had no idea if he would do it, though, since it's pretty dark subject matter.
"They told me he was studying to be a director and this was perfect for him. We watched three short films he made, two of which were dark and one of which was about a serial killer. That confirmed James definitely had this dark side, and it definitely sealed the deal for us. Sure enough, James read the material and responded to it immediately."