In addition, there are 20 unidentified fugitives whose names remain under seal until their arrests.

''A good number of them are Cuban and they will return to Cuba, where, as you know, there is no extradition policy and we have no way to get them back at this point,'' said Delaney, who headed the FBI's national healthcare fraud program before transferring to Miami in 2005.

U.S. Sen. Mel Martinez, R-Florida, a Pedro Pan Cuban exile who benefited like thousands of others from the Cuban Adjustment Act, is pushing legislation in Congress to double the criminal and civil penalties for Medicare fraud offenders. While Martinez said he didn't think Medicare fraud was strictly a ''Cuban issue,'' he also condemned the Cuban government for harboring the fugitives.

''My first thought is, it's one more reason why the Cuban government is an outlaw state because it allows fugitives of justice to find refuge there,'' Martinez said.

Cuban leaders Fidel Castro and his brother Raul Castro have rarely turned over fugitives of any kind.

Tracking down Medicare fugitives in countries such as the Dominican Republic, however, can be successful because they have extradition agreements with the United States. Federal authorities are working with the Dominican Republic to pursue the Benitez brothers and seize their extensive assets in Bavaro -- including a hotel called Cabañas Singapur.

Other assets include more tourist hotels, a Robinson R44 Raven helicopter, apartment complexes, luxury homes, supermarkets and a rental car agency -- registered under shell companies or straw names. Dominican officials started seizing properties and freezing their bank accounts in July in cooperation with the U.S. government, which plans to return the proceeds to Medicare.

On Friday, Justice Department prosecutors filed a proposed restraining order in federal court in Miami to ensure the Benitez brothers' assets are not sold or transferred to other parties.

The Benitez brothers' fugitive case has made headlines in the Dominican Republic not only because of the U.S. government's pursuit of their ill-gotten gains. Over the Fourth of July weekend, Carlos Benitez's daughter and son-in-law -- Yanelkis Benitez Ramirez and Lenin Linares Guerrero -- were kidnapped. Days later, Dominican authorities rescued the couple.

Meanwhile, FBI agents have traced the Benitez brothers to Havana, according to federal authorities.

In general, the FBI has had little luck capturing Medicare fugitives abroad in recent years. ''We've had no one returned on a healthcare fraud warrant that I'm aware of,'' Delaney said.

The one exception: In June 2004, authorities in the Dominican Republic turned over three Medicare fugitives -- Ruben Martinez; his daughter, Adriana Ramos, and her husband, Daniel Ramos -- who had fled to that country months before their indictment on fraud charges.

They were part of a Miami-Dade family racket headed by Martinez, 57, that was eventually convicted of bilking $14.5 million from Medicare by charging for bogus medical equipment orders such as hospital beds, oxygen tanks and foot arch supports in 2000-02. Federal authorities recovered $1 million from Dominican bank accounts, $900,000 from U.S. banks, real estate, jewelry and a Porsche Boxster.

''It was a classic case of international cooperation,'' said former federal prosecutor Wifredo Ferrer, the lead attorney in the prosecution of Martinez and 11 others. ``The three fugitives were Cuban nationals, not citizens of the Dominican Republic. The Dominican authorities deemed them persona non grata and expelled them to the United States.''