Contractors John Melching Jr. and Dallas Collins are based in Pennsylvania and Texas, respectively, and have never met, but they have something in common: They claim they have been cheated in the past year by a business transaction that involved Larry Polec, a Chicago-based surety-bond broker.

Polec is easy to spot. He is a former Michigan State basketball player who stands 6 ft, 8 in. Less easy to spot, however, are his roles in and links to an informal network of brokers and individual sureties whose controversial practices have allegedly cost contractors hundreds of thousands of dollars in lost premiums on bonds. Melching goes one step further: He says their practices put his company out of business.