Police in Germany began investigating the man in February after a mother came forward suspecting her son, now 17, had been abused.
The German man, 41, a former boy scouts supervisor, has not been identified by name. According to prosecutors, the abuse happened between 2010 and 2018 when the man targeted boys between the ages of 7-14. It is alleged that he even abused one boy 500 times.
The man is facing rape and battery charges in addition to the 696 counts of sexual assault against children.
The man was previously investigated between 2004 and 2007, according to prosecutors in the case, but that investigation was dropped for a lack of evidence.