All complaints of child abuse should be reported to the appropriate national authority.
An example of this would be the NCMEC (The National Center for Missing and Exploited Children) :
www.ncmec.com in the United States.
Since we are bound on German Jurisdiction, you may also contact:
Cybercrime
Hellwigstraße 8-10
66121 Saarbrücken
Tel.: 0681-962-2431
Fax: 0681-962-2445
Email: lpp222@polizei.slpol.de
Links regarding this case:
https://www.eco.de/services/internet-beschwerdestelle.html