Fake profiles / potential scammers

What is the formal procedure to report a fake profile and include proof or at least present own research that justifies suspicion?

(Google image search, name search, report-a-scammer sites, empty facebook page(!) and also behavior in written messages, etc. etc. etc.)

I have reasonable suspicion for a user and I am sure that I saw another profile photo (a man covered by tatoo) in a site with scammers.