Cologne daily Express reported on Wednesday that the girl from the Rhineland city of Mülheim installed a concealed video camera in her room after she had already been raped at least 17 times over several years.
Her stepfather, 70-year-old Greek Georgios A., denied the allegations, the paper reported.
“I have never seduced her, rather her me, I swear it,” he said through a Greek-German interpreter. “She must have put something in my drink. I don't remember anything.”
The state prosecutor accuses the man of seriously sexually assaulting the girl, who is now 13, at least 17 times between 2006 and May 2010.
“I want you. We'll do it now, my girl,” the man is alleged to have said before each attack.
The man also tied the girl up and threatened to kill her, prosecutors say.
The girl hatched her plan in May, hiding the camera in her room. When her stepfather raped her, the attack was recorded.
“You can clearly recognize in the images who is the perpetrator and who is the victim here,” judge Christoph Kaufmann said, according to the paper.
The girl showed the pictures to her teacher and her stepfather was promptly arrested. Because he continued to deny the charges, the victim had to testify for several hours on Tuesday, during which she clung to a teddy bear.
The girl now lives in a foster home and is "traumatised," the paper said. Her mother moved to another country after the case became public knowledge.
The court is expected to rule on the case on October 8.