Josef Fritzl (born 13 April 1935) is an Austrian criminal. He held his daughter captive in a basement dungeon that he built under his house. Fritzl made his daughter write letters to him and her mother, saying she had joined a cult. During the 24 years that he had her imprisoned, Fritzl raped his daughter often, and she had seven children by him. One of the baby boys died and Fritzl burned his body. The police eventually found out about his crimes when one of the children became very sick and he took her to the hospital.
Fritzl was tried and convicted on several charges, and he was sentenced to life imprisonment in a facility for the mentally ill in March 2009. Fritzl could become eligible for release after fifteen years, but he is expected to be in prison until he dies. A forensic psychiatrist diagnosed him with a personality disorder and a sexual disorder.