I have no idea if the OP is who he says he is. The telephone number and email address appear to be associated with the person who the OP says he is. This person appears to work for the FDA, and I am not sure why the FDA would be investigating anything to do with bitcoin, or even most crimes (the only crimes they investigate are those related to products the FDA regulates).

The person the OP claims to be does not appear to work in the law enforcement side of the FDA. I think there is a chance the OP is actually trying to get people to harass the person he is claiming to be by posting his contact information.

There are a number of private entities that I believe contract with government law enforcement agencies that help with the types of problems the OP claims to need help investigating. One of the well-known companies is chainanalysis.