Seamus C. Yorke is a forger.
Yorke was the boss of a group of criminals known for small-time criminal activity and the creation of fake IDs. After Reese took out the group, Fusco told Finch that the men were criminals and worked for Yorke.
Sameen Shaw, however, found Yorke first after Reese reportedly broke his legs and threw him off a rooftop. Shaw hung Yorke by his wrists to the ceiling of a garage in Queens, interrogating him on information about the whereabouts of Patrick Simmons. Finch came in with Fusco, and convinced Shaw that they find Reese first. Yorke told them that Alonzo Quinn is the only one who knows Simmons' exit strategy, and that everyone wants Quinn dead. Finch, Fusco, and Shaw left the garage, but kept Yorke hanging.