I was thinking about "Tyger, Tyger"... A password used inside an organization. Well, why would you put a password inside a crime organization? I dont think (but I'm not sure either) that Mafia has any password(s), for the simple fact that they know each-other.
A password, IMO, is used to recognize other members inside same organization.
This shows up that members inside "Tyger, Tyger Inc." does not know about each-other (mostly), only when working togheter, or in special moments (e.g. when one is dying, and there is other person(s) witnessing).

Using Reede Smith and cop driver pattern. Smith said used "Tyger, Tyger" password, having knowledge that if the drivers responds in the same way, they are both in same organization.
Why would others say "Tyger, Tyger" as their last words? Maybe just to know if they were killed by their organization.
Two exemple pops in my head right now:

    Todd Johnson to Patrick Jane
    Brett Partridge to Teresa Lisbon

Also, the head on this organization is Red John, as he said the first strophe on the poem, not only "Tyger, Tyger". Nobody else said more than first two words.

Thoughts?