Fugitive McLean millionaire Tom J. Billman used a former college roommate's name on a U.S. passport to flee to the coast of Spain, then dumped his longtime mistress, acquired a new one and lived a lavish lifestyle fueled by funds from secret Swiss bank accounts, federal authorities said yesterday.

Billman, who apparently still lives in Europe, continues to elude police pursuing him on fraud charges stemming from the collapse of his Community Savings & Loan Association in Bethesda in 1985.

Prosecutors disclosed that Billman's new girlfriend learned of his fugitive status and nearly succeeded in turning him in.

At another point in the chase, "We believed we were only hours behind him," said Maryland U.S. Attorney Breckinridge L. Willcox.

But Billman, 50, a balding, heavyset man, has managed to keep at least one step ahead of authorities for the last 18 months. In the nation's numerous S&L scandals, Billman is thought to be the only fugitive overseas. A $200,000 reward has been offered for information leading to his arrest and extradition.

At large since a Montgomery County jury entered a $112 million judgment against him in the collapse of Community S&L, Billman, former president of the thrift, was indicted in January on federal charges of defrauding its depositors of $106 million. At the same time, he was charged with passport fraud, but that indictment was kept sealed until yesterday, officials said, to prevent Billman from learning that authorities knew his alias.

With the unsealing of the indictment, prosecutors disclosed that Billman has lived in the popular Costa Del Sol region of southern Spain under the alias George M. Lady, the name of one of his roommates at George Washington University in the late 1950s.

In Spain, Billman lived in luxury, Willcox said, renting a seaside condominium apartment in the port of Estepona, where he kept two yachts -- a $318,000, 44-foot motor launch with a two-member crew, and a $102,000, 45-foot sailboat.

Using the name George Lady, Billman established a business and retained a set of attorneys in Gibraltar, Willcox said, drawing on funds from secret Swiss bank accounts where he allegedly deposited $22 million siphoned from his now-defunct Community S&L.

According to the indictment unsealed yesterday, Billman obtained his phony passport in late 1985, several months after the collapse of Community. Willcox said Billman apparently anticipated fleeing prosecution and held the passport "in reserve" before using it in Europe.

Getting the fake passport was easy, Willcox said. Billman obtained a copy of George Lady's birth certificate, available from public records in the District, where he was born, Willcox said. Similarly, he obtained a Virginia driver's license in Lady's name, Willcox said. Armed with those documents, he received a passport with no difficulty, the prosecutor added.

The real George Lady, now an economics professor at Temple University in Philadelphia, was unaware that his name was being used by Billman, according to Willcox. Lady did not have a current passport of his own, "and Billman knew it," Willcox said.

Lady could not be reached yesterday for comment.

When Billman fled to Europe in late 1988, he left behind his wife but kept in touch with Barbara McKinney, a former Community officer described in court documents as his mistress. He sent her $500,000 from Switzerland, funds that prosecutors are trying to retrieve.

Billman sent McKinney a "goodbye note" sometime later, Willcox said, and is thought to have "severed all relationships in the U.S."

In Spain, Billman allegedly acquired a new girlfriend, described by Willcox as an attractive European in her thirties or forties. Billman left her abruptly last October, Willcox said, apparently after learning that authorities were close on his trail. The woman, however, did not learn that Billman was a fugitive until Spanish police approached her some time later, Willcox said.

"She was angling for the reward money," Willcox said, and told police she was expecting him to come back to her. "We were on the scene and hoped he would return," said Willcox, but he never did.

Willcox said that in another "Lady event," which he would not further describe, police think they "were only hours behind" Billman but again failed to apprehend him.

Primarily, he said, authorities have tried to trace Billman's movements through money transfers from his Swiss accounts.

Willcox said he thinks that Billman is no longer using the George Lady alias and has adopted a new identity.

Willcox also said U.S. authorities want maximum publicity about Billman's fugitive status and personal habits, hoping that someone will spot him and notify police.

He said, for example, that Billman is a yachting enthusiast, "and we are hoping to place stories {about him} in yachting magazines."

U.S. marshals, who along with postal inspectors and State Department investigators are pursuing leads on Billman, describe him as 5 foot 9 and 195 pounds. He has brown eyes, is bald and, when seen in December, had a beard, officials said.

A statement issued by Willcox's office said Billman has chronic neck and back pain and "frequently seeks chiropractic treatment."

Billman regularly reads the Internatonal Herald Tribune and other English-language papers with financial news, the statement said, and he enjoys "casino gambling, listening to country and western music and reading spy novels. He is known to be fond of gin."

Information is being received by the U.S. Marshals Service at (202) 307-9100 and (800) 336-0102.