and was staying with a friend; she warned her parents not to look for her or she would leave the country. Fritzl told police that she had most likely joined a cult. Over the next 24 years, Fritzl visited Elisabeth in the hidden chamber almost every day, or a minimum of three times a week, bringing food and other supplies, and repeatedly raping her. Elisabeth gave birth to seven children during her captivity. One child died shortly after birth, and three—Lisa, Monika, and Alexander—were removed from the chamber as infants to live with Fritzl and his wife, who were approved by local social services authorities as their foster parents. Officials said that Fritzl "very plausibly" explained how three of his infant grandchildren had appeared on his doorstep. The family received regular visits from social workers, who saw and heard nothing to arouse their suspicions. Following the fourth child's birth in 1994, Fritzl allowed the enlargement of the prison, from , putting Elisabeth and her children to work digging out soil with their bare hands for years. The captives had a television, a radio, and a videocassette player. Food could be stored in a refrigerator and cooked or heated on hot plates. Elisabeth taught the children to read and write. At times, Fritzl would punish the family by shutting off their lights or refusing to deliver food for days at a time. Fritzl told Elisabeth and the three children who remained (Kerstin, Stefan, and Felix) that they would be gassed if they tried to escape. Investigators concluded that this was an empty threat to frighten the victims; there was no gas supply to the basement. He also told them that they would be electrocuted if they tried to meddle with the cellar door. According to Fritzl's sister-in-law Christine, he went into the basement every morning at 09:00, ostensibly to draw plans for machines which he sold to manufacturing firms. He often stayed there for the night and did not allow his wife to bring him coffee. A tenant who rented a ground floor room in the house for twelve years claimed to hear noises from the basement, which Fritzl said were caused by the "faulty pipes" or the gas heating system. Discovery On 19 April 2008, Fritzl agreed to seek medical attention after Kerstin, Elisabeth's eldest daughter, fell unconscious. Elisabeth helped him carry Kerstin out of the chamber and saw the