Even Vellos said he had been trying to figure all this out but couldn't find evidence.
Hireshmont knew the name of the organization, he knew Erasmus either was a leader in it (or if he wasn't, would be recruited soon enough), and he knew they did some info funneling and advie-hunting. He didn't know Erasmus was THE leader, he didn't know they were so politicized, and he didn't realize they were operating in the Lurias quite as much as they were.
Tying it to Erasmus was harder than you'd think. The Lurian confessions were a lucky break, though Hireshmont had Erasmus pinned before he received word of the actual confessions themselves. As soon as he heard about issues in Luria he connected the dots.
