You`re most welcome.
PN is my mistake, its the German acronym for PM - personal message. Sorry.
Well, on the inquiry...I doubt that there is a mechanism/law that allows you to do so. However, I´d try to seek contact directly with them through the contact details on their website. I was in a class held by one of the BFUs investigators two weeks ago and he seemed to be a fairly nice guy.
They will surely not give you any details if you can´t prove who you are, but they will be able tell you how this could be done. I´m not an expert in this field and MAYBE there is something in the law preventing them to disclose details early on...one path that springs to mind is btw to ask the US embassy in Germany to assist you.
Contact Us | United States Diplomatic Mission to Germany
If you want to call them, our time zone is UTC +2,(with DST effective now) I would think the best chances to reach them will be between 0800 to 1600 local time. Thats 0600 to 1400 UTC.