The man, aged between about 25 and 40, is seen repeatedly molesting the baby, thought to be between three and eight months old at the time, in videos and photos obtained by the Federal Criminal Police (BKA).
Although the pictures date from around 2005, detectives say they are concerned the man could still be abusing the child now.
They say he speaks German with a bit of a lisp. Although detectives have been trying to track him down since June, they have renewed their call for help from the public, as so far they have not made any progress.
The baby – called Sophie or Kim, say detectives, was abused in a bathroom, on a nappy changing table and on the floor. Images released by the BKA show details of the decorated bathroom tiles and the baby's clothing, as well as the man's face and hands. He is wearing a thin, gold-coloured ring on the small finger of his left hand.
Germany's strict privacy laws also apply to criminal suspects, which in most cases mean the media cannot print their photos until conviction, meaning the decision to release these pictures is particularly unusual.
It evokes memories of another case the German police were involved in: The 2007 arrest in Thailand of paedophile Christopher Paul Neil.
In that case, German police were able to unscramble photos of Neil's disguised face in pictures of him molesting young boys.
After a search, the Canadian was captured and convicted. He is now imprisoned in Thailand.
Anyone with information on the current case is asked to contact the BKA on +49 (0) 611 55-11155.