The True Story of the Netflix movie THE CHALK LINE is one of the most infamous true crimes of this century: The Monster of Amstetten, Josef Fritzl. Read more about how this true crime inspired the story in The Chalk Line (org. title Jaula) here. *Obviously, this will have spoilers for the Netflix movie*

When watching the Netflix movie THE CHALK LINE, you’ll probably be reminded of a true crime. That’s because the movie is based on a very true story. Of course, the below will include many The Chalk Line spoilers.

If you’re simply looking for a review of the Netflix movie, click here for our The Chalk Line movie review >

More on the true crime that inspired The Chalk Line

The true crime that inspired The Chalk Line is that of Josef Fritzl (aka The Monster of Amstetten), who held his own daughter, Elisabeth, captive in a basement for 24 years. There, he abused and raped her, which resulted in a total of seven children being born.

One child was killed by Fritzl shortly after being born and burned in an incinerator.

Three children lived with Elisabeth in the basement, where she taught them to read and write.

Finally, three children lived upstairs in the house with Josef Fritzl as “foundlings”.

He became a foster parent along with his wife Rosemarie. Since Rosemarie was also the biological mother of Elisabeth, these children were her grandchildren. For Fritzl, they were both his children and his grandchildren.

Elements that are the same in The Chalk Line and the Fritzl case

There are three core elements in The Chalk Line that line up almost perfectly with the true crimes of Josef Fritzl.

  1. An unknown basement has been turned into a prison. There is more than one person that has been held captive for many years. This was also the case in Amstetten.
  2. The child in The Chalk Line is the result of the kidnapper raping the original victim, which means she has lived her whole life in this basement. The same was the case for three of Elisabeth Fritzl’s children.
  3. When the child had a medical emergency involving kidney failure, the child was taken out of the basement to get help. This was how one of the children got out and became the beginning of the end for Elisabeth’s decades of captivity.

These three elements are key to both Josef Fritzl’s true crime and the story in The Chalk Line.

How is The Chalk Line different from the true story?

Overall, the location and all the names have been changed. Actually, the location still has to do with a basement, but in a different country and different setting. Still, many of the brutal details are real – just like several of the very gruesome details of the real Josef Fritzl case have been omitted.

Gruesome, as the real story is even more grotesque than the one shown in The Chalk Line.

In the recently released Australian Netflix movie The Stranger we also got a true crime story where names and details about the crime had been altered.


Our review of the Netflix movie The Stranger here >

The main differences between the real criminal Josef Fritzl aka “The Monster of Amstetten” and the criminal in The Chalk Line are these:

  • The real case took place in Amstetten in Austria.
    • This takes place in Spain.
  • Josef Fritzl imprisoned his own daughter.
    • In this Netflix movie, a child from another country is abducted.
  • The original victim, Elisabeth Fritzl, survived 24 years of captivity in a basement.
    • The original victim, Ingrid, has died in The Chalk Line.
  • Seven children were born by Elisabeth while in captivity.
    • In the movie, we only see one child, Clara.

There are probably many more details, but these are the most obvious ones.

Did Josef Fritzl use chalk lines?

The element that inspired the title of this new Netflix movie The Chalk Line, does not seem to have been used by Josef Fritzl.

Of course, the original title of this Spanish movie is Jaula which translates into cage or even jail.

It appears the chalk lines in this movie were used to illustrate the brainwashing done by the criminal. When a kidnapper can have a hold on someone that is so strong that a simple chalk line will keep them in, some serious brainwashing and brutal conditioning have taken place.

More on Josef Fritzl

I am by no means an expert on “The Monster of Amstetten”, but I do remember when Josef Fritzl and the case hit the news in 2008. What I didn’t know were details such as the fact that the last thing Elisabeth did before being captured, was help put her own jail door in place.

Of course, she didn’t know what was happening. She was just helping her father with a heavy door in the basement. The next thing she knew, she woke up on the other side of the door, which was now locked.

A simple Google search of Josef Fritzl will lead to much more information. As for Elisabeth Fritzl and her six remaining children, they are trying their best to live real lives. I hope this is possible, but cannot imagine it can be easy.

Check out our TRUE CRIME tag for more movies, series, and documentaries >

I write reviews and recaps on Heaven of Horror. And yes, it does happen that I find myself screaming, when watching a good horror movie. I love psychological horror, survival horror and kick-ass women. Also, I have a huge soft spot for a good horror-comedy. Oh yeah, and I absolutely HATE when animals are harmed in movies, so I will immediately think less of any movie, where animals are harmed for entertainment (even if the animals are just really good actors). Fortunately, horror doesn't use this nearly as much as comedy. And people assume horror lovers are the messed up ones. Go figure!
Karina "ScreamQueen" Adelgaard
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