Gomez said some immigrants came with survival instincts cultivated under the totalitarian regime of Fidel Castro. They distrusted and cheated his communist government as a way of getting around the system, but they did not shed that behavior when they came to Miami simply because they were living in a free country.

''They are a product of their element,'' Gomez said. ``It's a very difficult habit to break.''

FBI agents not only have a hard time tracking down Medicare fugitives, but also their money.

Law enforcement officials suspect that most Medicare defendants who flee -- such as the Benitezes -- launder their money offshore.

Prosecutor Eric Bustillo, chief of the economic crimes section at the U.S. attorney's office in Miami, said that once Medicare money is withdrawn from local banks it's difficult for federal authorities to follow it.

''It's the opposite of drug trafficking,'' Bustillo said. ``The drug traffickers get paid in cash, so they have to find businesses and other ways to launder it. The Medicare providers must receive all of their payments in checks or wire transfers to a designated bank account. So the money can be tracked down to that bank. But they immediately cash it out. And once they do that, who knows where it goes?''

Federal authorities and money-laundering experts know some of the Medicare fugitives' money ends up outside the United States. Case in point: the Benitezes' assets in the Dominican Republic.

But unless authorities can identify the laundered Medicare millions -- bank accounts, real estate, cars, boats -- they can't take legal action to go after the assets.

According to money-laundering experts, it's easy to move dirty money to certain countries.

For a pittance, Medicare violators can hire lawyers offshore to set up shell companies and assist in the opening of related bank accounts, said Brett Wolf, a U.S. money-laundering analyst with Complinet, a London-based firm that helps financial institutions meet their compliance obligations.

''Cash smuggling is almost certainly playing a role,'' Wolf said. ``Considering the heavily state-controlled nature of Cuba's financial network, it's very unlikely that these Medicare funds are being moved through the formal banking system.''

Fugitives, based in a country such as the Bahamas or Mexico where there is regular travel to Cuba, can go back and forth to the island, carrying thousands in cash that can be exchanged for a currency called CUCs (pronounced ``kooks'').

But it would be risky business for fugitives carrying a lot of cash, say $50,000, to attempt to bribe communist government officials unless they have connections.

Still, a Medicare fugitive with hundreds of thousands or even millions of dollars stashed in offshore accounts could live like a tycoon in Cuba, where the monthly salary averages $17.

Coming Sunday: The politics of Medicare reform.