According to German media reports, a man claiming to be a former member of ISIS has leaked files containing information on thousands of ISIS members.
Among the names are several members who were involved in the Paris attacks last November.
Investigators say 3 men listed in the files were identified in connection with the deadly attack at the Bataclan Theater where 90 people were killed.
Sky News says a former ISIS member dropped off the files at their offices.
The news outlet claims there are at least 4 Americans on the list. However, terrorism experts have yet to confirm the authenticity of the files.