SARs are warnings, flags. They do not indicate a crime has been committed. And the Dept of Justice does not issue SARs.

I think the OP is talking about BitMex. I work at a crypto exchange and a large part of our team is dedicated to monitoring and reporting(through SARs and STRs) suspicious activity.

Op is likely referring to the fact that, as shown by the recent FinCEN leaks, big banks like HSBC and Deutsche Bank have processed likely (and likely obviously), but filed SARs so they don't even get a slap on the hand.