FORT McCOY, Wis. (AP) _ The World War II-vintage barracks are hollow and silent, but a 12-foot fence with razor-sharp wire still surrounds the buildings where thousands of Cuban refugees began their stay in the United States a decade ago.

When Cuban President Fidel Castro opened the port of Mariel - and his prisons - in 1980, about 14,000 of the 125,000 refugees who came to the United States were sent to this southwestern Wisconsin Army base for processing.

One was Julio Gonzalez, the 36-year-old drifter charged last week with torching an illegal New York City social club and killing 87 people.

His arrest has revived the debate over the cost to the nation of accepting the refugees who arrived on the shores of Florida in boats and rafts in what was called the Freedom Flotilla.

Duke Austin, an Immigration and Naturalization Service spokesman, said about 2,600 Mariel Cubans are being held by the INS; 4,000 others are serving prison time for for felonies committed in the United States.

''I would say there is probably in excess of at least 12,000 that have been involved in criminal activity,'' he said.

But Barbara Biebel, director of refugee, migration and Hispanic services for the Catholic Diocese of Green Bay, said the criminal involvement of the refugees has been exaggerated.

''Probably for every horror story like the New York firebombing, there are so many success stories of people starting a family or a business,'' she said.

Darrell Neitzel, a civilian Fort McCoy employee who was in charge of plumbing for the two-story barracks where the Cubans were herded, remembered the refugees' fears.

''They were afraid about everything. They didn't know what was going to happen to them next. They didn't know if there was going to be a firing squad that was going to shoot them the next morning or what,'' Neitzel said.

Little is known about Gonzalez's activities at Fort McCoy, including how long he was there.

''He never tried to become a citizen,'' Austin said. ''We had never had any problems with him in the 10 years he has been here.''

About 80,000 of the 125,000 Mariel refugees have become U.S. citizens, Austin said.

Most of the Cubans processed through Fort McCoy and detention centers elsewhere in the nation eventually left for cities with larger Hispanic communities such as Miami and New York.

Jesus Labrador, 48, stayed, moving just 35 miles away from the Army installation to La Crosse.

Labrador, who spent two months at Fort McCoy, went to a trade school, learned English and carpentry and said he did fine until he stumbled in 1986 when he was convicted of selling cocaine and spent two years in prison.

Today, Labrador works a $4-an-hour job with a small company that makes furniture.

''I have my house, my woman. ... I like it here. I love this city,'' he said.

Other refugees have not fared as well. Since 1985, the United States has returned 375 refugees to Cuba, including 40 who never were released during their time in the United States, Austin said.

Even a decade after the boatlift, refugees involved in criminal cases still command sensational news media coverage.

Andres P. Montelier, 27, was arrested in January and charged with murder in the stabbing and beating death of an elderly Milwaukee woman, whose body was found with a large ''M'' engraved in the flesh. Montelier is awaiting trial.

Lene Cespedes-Torres was convicted of murder shortly after his acceptance in the United States. One month after a background check at Fort McCoy, he was released into the custody of a family in nearby Tomah. A month later, he was arrested for strangling the woman who agreed to sponsor him in the United States. Cespedes-Torres is serving a life term in prison.

Immigration officials estimate the total cost to U.S. taxpayers for INS services and justice for the Mariel refugees easily exceeds $1 billion.

''I don't know how you weigh the advantages and disadvantages,'' Austin said. ''Certainly, there were a lot of good people. Certainly, there has been an over-characterization of the boat people as a bunch of criminals and misfits.

''But there was an element in there that was extremely expensive to the American public.''