I wonder what Wiley meant when he mentioned the Stonemasons. Perhaps that was a slip of tongue. Could the Defias gang be related to the Stonemasons? Only one man would know for sure: Mathias Shaw, head of SI:7. Show him Wiley's Note and see if he has anything to add to this growing mystery. If you have trouble finding Shaw, check the Barracks in Old Town.
This matter might be more complex than Stoutmantle realizes.