At least two sizeable Connecticut law firms have fallen victim to sophisticated international swindlers posing as major European or Chinese companies in need of debt collection help.

The initial inquiry is often in an e-mail, which offers the law firm a chance to work for a large foreign corporation with several million dollars in unpaid bills in the U.S. An attorney signs a formal-looking retainer agreement. Suddenly, he receives a six-figure “debt payment” sent by one of the so-called client’s customers, in the form of an authentic-looking bank check.