Is John Graff From ‘The Watcher’ Based on a Real Person?

The bodies of John List’s family had been in the house since November. His wife Helen, their children Patricia, Fred, and John Jr., as well as Helen’s mother had all been shot. Prior to their murder, John List Sr. “had announced that they were going on a family trip, had stopped the paper and milk deliveries,” promptly killed his entire family then confessed in a letter to his pastor he left in his study. Like the fictional John Graff, John List Sr. went to a Lutheran church. Also like John Graff, John List Sr. was in dire financial straits.

Source: https://www.distractify.com/p/johh-graff-real-person-the-watcher