William Collins

An agent in the Chicago office of the A.T.F., Bill Collins comes across as a sleazy, nosy government agent who fancies himself as Eliot Ness. He is investigating a gun-running operation, but has run into a lot of dead leads. Desperate for help, he 'enlists' Rally and May's help by holding up the gun shop's license as insurance.
Although they had success at first by shutting down a distribution point in Chicago, Jonathan Washington, the lone witness, along with five A.T.F. agents, are murdered in a safehouse by the assassin Natasha Radinov, using Collins' cardkey and access code to gain entry. Now the investigation is due to be closed and Collins soon discovers a conspiracy within the A.T.F., which involves his superior George Black and mayoral candidate Edward Haints who has Rally as a target. (From Wikipedia)