based on a true story?

I saw where Sisto said in an interview with ShockYa.com "...the story was inspired by an article that we read, in which a homeless man was living inside a crawlspace in someone’s house for years."

I researched that a bit and believe it or not it doesn't seem that uncommon actually. I found quite a few articles.

Here's a good one with some creepy instances: http://listverse.com/2015/03/31/10-creepy-stories-of-intruders-hiding-in-peoples-homes/