Watch out with accusations... There has been wrath from above for less 
. No proof equals no right of accusation.
You can send the accusation to the Titans with nothing more then suscipions or gut feelings. If you want to vent accusations in game against players, then yes you really should have some proof. Of course you can IC accuse anyone you want of being a traitor as well, you don't need proof to try and implicate a characters.
