BRUSSELS — When Regina L. Hayes, a retiree in Roebuck, S.C., a small town outside Spartanburg, transferred $75,000 from her savings to an investment fund, she thought she was helping Christian miners in Africa fend off competition from conglomerates. She was promised a return of 10 percent a year.

But before long, she and fellow investors learned that they had become victims of a Ponzi-like scheme — one, it turns out, that leads back to a former high-ranking European Union official.

The former official, John Dalli, 68, is a longtime power broker in Malta, the tiniest of the 28 countries of the European Union. In 2012, he was forced out as the European Union’s health commissioner in a case involving alleged kickbacks.

It was a big scandal at the time. But European investigators now believe that Mr. Dalli was linked to a separate fraud scheme — one that reached from Malta to the Bahamas to South Carolina, and that bilked investors including Ms. Hayes of at least $1.5 million.