Police circulated images of the girl found on the dark web
Police made the extraordinary decision to show the photo of the suspect's victim in an attempt to track him down and prevent further abuse.
The child and her mother saw the images when they were posted online and shown on television and visited their local police station in Germany.
A 24-year-old man - identified in the media as the mother's boyfriend - was detained hours after the nation-wide manhunt began, and was due to go before a judge today, according to Frankfurt chief prosecutor Georg Ungefuk.
Ungefuk said: "The suspect is believed to have seriously sexually abused the child a total of nine times, to have made films of the abuse and then distributed them."
The man's apartment in the Wesermarsch district of Lower Saxony was searched and evidence seized. The dark web is a part of the internet not accessible via search engine and is often used by drug dealers and paedophiles to avoid detection.
Authorities took the unusual step of distributing the photograph of the girl in this case because they had run out of other options.
The mother contacted the police because she knew the game was up - that many other people would know who the child was and who the mother was so she jumped in first and is now trying to whitewash herself.