A 33-month-long life on the run, which included luxury apartments in London and Frankfurt, hotel suites in the Caribbean and well-appointed hideaways elsewhere, came to an end this week for Spanish tycoon Jose Maria Ruiz Mateos when he returned to Madrid accompanied by two detectives and was committed to a cell in the maximum security wing of a prison near the Spanish capital.

The somber homecoming ended a bizarre chapter in which the country's richest man became its most celebrated fugitive from justice. It opened a new one that promises a major legal battle and may hold unforeseen political consequences.

Ruiz Mateos was the founder and chairman of Spain's largest private holding -- the Rumasa business empire that was built up in the early 1960s from modest sherry vineyards to include banks, real estate companies, shipping interests, hotel chains and department stores.

All 230 companies in the vast group were expropriated by the Socialist government in February 1983 on the grounds that the conglomerate was near collapse and that its bankruptcy could rock the nation's entire financial system. The following month, Ruiz Mateos left Spain as officials began to examine the Rumasa books.

While judges began to issue orders for his arrest on charges of fraud, embezzlement, currency smuggling and "insulting the head of state," Ruiz Mateos continued to figure prominently in the Spanish media, giving several interviews in which he repeated serious allegations about business rivals, politicians and King Juan Carlos.

Early last Sunday morning the 54-year-old businessman was imprisoned in the town of Alcala de Henares after a brief midnight appearance before a Madrid investigating judge. He was taken before the judge immediately after arriving aboard a chartered flight from Frankfurt, his base in recent months, after courts in West Germany upheld an extradition request.

As he left the offices of an investigating judge here Monday, Ruiz Mateos told onlookers, "I'll win; reason is on my side. The government will fall."

The return of Ruiz Mateos again brings up the issue of the expropriation of Rumasa, which was no less controversial than the tycoon's subsequent nomadic existence and the torrent of accusations he leveled at the Spanish establishment. The confiscation by the Socialist government of the wide-ranging Rumasa assets was hotly contested by Spain's conservative opposition party, but its legality was upheld by the country's top legal body, the Supreme Tribunal.

Since then, attention has focused on "reprivatizing" the Rumasa companies, which following the expropriation were technically owned by the state. Among the main beneficiaries of what was billed as the "sale of the century" were non-Spanish groups that bought up Rumasa companies after they had been refinanced with public money.

The sale of the conglomerate's assets has prompted a lively debate in the Spanish press about favoritism as well as allegations that the state takeover exacerbated the group's financial difficulties. When the reprivatizing process began last year, authorities put Rumasa's accumulated losses at $2.6 billion. Officials have said that $3 billion in public funds has been spent on refloating the holding.

The Madrid investigating judge who remanded Ruiz Mateos into custody is likely to press charges on two counts of fraud -- one involving false balance-sheet data and a second concerning exaggerated claims for his bank's assets. These were the only charges that were accepted by the West German courts as grounds for extradition, and they carry maximum six-year sentences.

Although trial proceedings are not expected to begin for several months, according to the Spanish press, the Ruiz Mateos case is certain to dominate local interest. Not least of the potentially explosive aspects of the proceedings is the web of highly placed Spaniards who accepted directorships and senior positions in Rumasa companies.

Ruiz Mateos was in the Spanish public eye long before the extradition order. He is a self-made man who turned the logo of his Rumasa empire -- a busy bee -- into a trademark that was as familiar to Spaniards as bullfight posters.

In the late 1970s Ruiz Mateos, who was Rumasa's majority shareholder, filed the highest income tax returns in Spain. His fabulous wealth was as celebrated as his pious Catholicism; he was a prominent member of the Roman Catholic lay organization Opus Dei.

A frequent allegation made by Ruiz Mateos in interviews and court statements while he fought extradition proceedings was that he was the victim of a conspiracy organized by banking and business rivals who envied his success and who plotted his downfall with the Socialist government.