Why Was Elisabeth Fritzl: Imprisoned As A Sex Slave?

Elisabeth Fritzl: Imprisoned As A Sex Slave By Her Father For 24 Years
At the age of 17, Elisabeth ran away from home. She went to to stay with her friend in Vienna. After three weeks of being absent at home, she was brought back home by police. Why did Elisabeth run away from home?
During her father's trial which took place 24 years later, it emerged Elisabeth was continually abused by her father from a tender age. Her father, Joseph Fritzl, began abusing her at the age of 11. She had always threatened to run away from home, and the couple times she did so she would be brought back home by the police.
Her father was born in April 9, 1935 in Amstetten, Austria. At the age of 21 she married Elizabeth's mother, Rosemarie, who was 17 years old.
At the age of 19, Elisabeth's life took an unexpected dramatic turn.
In August 1984, her father asked her to help him carry the door to the basement. She didn't know she was lured by her father into carrying the door which would lock her in the basement for over 20 years.
At the basement, she held the door while her father fixed it. After completing the job he held a cloth on her nose and mouth which was soaked with ether. She fell unconscious. When she woke up she found herself in the basement, the door closed.
On the second day, "after her incarceration, he put an iron chain around her stomach, attaching it to a pole "so that she had no chance of
She didn't stay for long. Her coming home was to leave her children in the arms of her parents in the respective years they were born. They were brought home as toddlers. Since her mother never knew her daughter was imprisoned in the basement, Fritzl statement seems to suggest that Rosemarie wasn't in the house when her daughter brought in her children.
In the basement, the first three children - Lisa, Monika and Alexander - were not lucky. They faced a lot of difficulties followed by constant abuse from their father. Their mother taught them how to read and write.
In April 2008, the eldest daughter, Kerstin, fell sick and ultimately became unconscious. Elisabeth helped her father to carry her daughter upstairs. She saw the outside light for the first time after 24 years in captivity. He returned her to the dungeon and took her daughter to the nearest hospital. The daughter was admitted in a critical condition as a result of kidney failure. At the office, Fritzl talked with Dr. Albert Reiter about the girl's condition and a letter Fritzl claimed was sent by his