Call it the mystery of the European sugar triangle.

It began when Belgian customs officials examined shipping records for dozens of giant tanker trucks that outlined an odd, triangular journey across Europe. The trucks, each carrying 22 tons of liquid sugar, swung through eight nations and covered a driving distance of roughly 2,500 miles from a Belgian sugar refinery to Croatia and back  instead of taking the most direct, 900-mile route.

Along the way the trucks made a brief stop in Kaliningrad, a grim and bustling Russian border checkpoint on the Baltic Sea.

Suddenly the sugar triangle made sense to them. Because Russia, and not Croatia, was listed as the intended destination, the shipments qualified for valuable special payments known as export rebates from the European Union’s farm subsidy program.

Some 200 shipments roared along this route over a three-year-period, investigators say, earning 3 million euros in refunds (about $4.5 million) for the Belgian sugar maker Beneo-Orafti. In the spring, dozens of Belgian and European investigators raided the company’s offices, freezing half of its refunds and initiating an investigation that could cost the company the remaining 1.5 million euros, and possibly more.