The case is reminiscent of Austrian Josef Fritzl, who held his daughter captive in a basement prison for 24 years, while fathering four children with her, including one who died in infancy.
The German girl, who lived in Heidelberg, tracked down her biological father on the internet and made contact with him. She flew to South Africa in February, where her nightmare began.
According to the South African daily Rapport, the girl was held in her father's home in Muizenberg, just south of Cape Town.
For two months, the man allegedly raped her as often as three times a night. He also threatened her with a knife and would use it to cut off her clothes when she wouldn't cooperate with him.
The teen escaped when she and her father went for an overnight visit with friends. She wrote a letter to the couple, explaining her plight. The father became violent and threatened the couple when they told him he wouldn't be allowed to see her again, the newspaper reported.
Now facing charges of incest including rape and assault, the 53-year-old was released on a R1,000 (€90) bail. According to local police, he will appear in court again on August 7.
The girl is now in protective custody with her brother, who flew from Heidelberg in Baden Württemberg to be with her after she was rescued from her father.
Police are withholding names for legal reasons.