Screenwriter Donald E. Westlake based the character of Stephanie on his real-life teenage stepdaughter, who he was having difficulty getting along with at the time.
Loosely based on the story of John List, the New Jersey man who killed his family in 1971, and was on the run until 1989, when his profile on the television show America's Most Wanted: America Fights Back (1988) resulted in his capture. The episode is: John Emil List/John Riccardi (1989).
John List (1925-2008) was the real-life killer who inspired the film. Like the film, List killed his family in their suburban home and went on to live under a false identity. Also similar to the film, List continued to leave the house "for work" to keep up appearances with his wife after losing his job. He was finally apprehended after 18 years in hiding, and died in prison custody.
The first draft of the screenplay featured flashbacks which helped explain Jerry Blake's (Terry O'Quinn's) abused childhood, that was instrumental in his becoming a killer.