The Thorn In Each Other's Sides
Mulderig hates Popeye, and the feeling is mutual. When Captain Simonson breaks the news to Federal Agent Mulderig that he'll be working on a case with Popeye, he basically has smoke coming out of his ears. But hey, Popeye has good hunches, Simonson reminds him. Mulderig snarls:
"His brilliant hunches cost the life of a good cop."
If we've learned anything from police dramas and television cop procedurals, it's that getting another cop killed is a cardinal sin for a man in blue. Here, Mulderig's giving us some important info: Popeye may be a hard-working guy, but he's none too careful and doesn't really break a sweat for anything but the case at hand. And that can be dangerous for everyone else.
Throughout the film, Mulderig (played by Bill Hickman, who was also in the west coast version of The French Connection, AKA, 1968's Bullitt) sits in the backseats of surveillance cars, being cranky, and giving Popeye a hard time. Why don't you just give up? he asks, over and over.
Mulderig isn't a fully developed character so much as the scowling ghost of Popeye's iffy conscience… until, of course, the agent's shot dead in the final scene.