I'm gonna do my best to sum up this story and you can dive deeper in the video below or at the links I've included.
A family buys a house in New Jersey. It's 106 years old and it's kind of a fixer-upper. As soon as they buy it, they start getting creepy letters from someone who calls themselves, "The Watcher."
The letters say things like, "Do you know the secrets of the house? Do you know why the house brought you there? My grandfather watched the house in the 20s, my father watched the house in the 60s and now it's my turn to watch."
They got more letters that proved this person had been actually watching the house. The letters described which child was in which bedroom, who the family had hired to do the upgrades. "The Watcher" told them that if their kids were playing in the basement, the parents wouldn't be able to hear them scream.
The family, of course, was terrified. They called the police after the first letter arrived but the police were baffled. They couldn't figure out if "The Watcher" was a neighbor with a grudge, or someone driving by playing an elaborate sick joke. They had no idea. They talked to neighbors and some seemed likely suspects but they all checked out.
The owners kept getting letters and finally sold the house and no one ever found out who "The Watcher" was.
Freaking creepy. The funny thing is, you just know it's some harmless oddball old lady or some lonely kid living nearby who got a kick out of scaring them.
Or was it?
More at these links.
And here's a video.