The Americans stayed at some of the finest hotels in Milan, sometimes for as long as six weeks, ringing up tabs of as much as $500 a day on Diners Club accounts created to match their recently forged identities, according to Italian court documents and other records. Then, after abducting their target and flying him to Cairo under the noses of Italian police, some of them rounded out their European trip with long weekends in Venice and Florence before leaving the country, the records show.

Milan prosecutors and police spent the last two years documenting Americans' role in the Feb. 17, 2003 disappearance of Hussan Mustafa Omar Nasr, 42, an Egyptian cleric. On Thursday, a Milan judge ruled that there was enough evidence to warrant the arrest of 13 suspected CIA operatives on kidnapping charges.

The Americans' whereabouts are unknown, and Italian authorities acknowledged that the odds were slim that they would ever be taken into custody. The CIA has declined to comment.

While most of the operatives apparently used false identities, they left a long trail of paper and electronic records that enabled Italian investigators to retrace their movements in detail. Posing as tourists and business travelers, the Americans often stayed in the same five-star hotels, rarely paid in cash, gave their frequent traveler account numbers to desk clerks and made dozens of calls from unsecure phones in their rooms.

During January 2003, they were regular patrons at the Hotel Principe di Savoia in Milan, which bills itself as "one of the world's most luxuriously appointed hotels" and features a marble-lined spa and minibar Cokes that cost about $10. Seven of the Americans stayed at the 80-year-old hotel for periods ranging from three days to three weeks at nightly rates of about $450, racking up total expenses of more than $42,000 there.

The first operative came to Milan on Dec. 7, 2002 and stayed for 11 days at the Milan Westin Palace, according to the court documents. The others started arriving in early January and by Feb. 1 almost all of them were in place. They eschewed safe houses and private homes, bunking instead at places such as the Milan Hilton ($340 a night) and the Star Hotel Rosa ($325 a night).

In early February, most of the operatives gathered for a rendezvous in La Spezia, an Italian seaside resort town on the Ligurian coast, almost a three-hour drive from Milan. Hotel records show that they checked into two hotels in La Spezia but stayed for only a few hours before departing. Some of them then drove to Florence for an overnight trip, but the rest returned to Milan.

According to Milan investigators, there were two distinct groups. One crew of six was in charge of planning and surveillance, checking out possible escape routes and procuring cell phones. Each of those people left the country about a week before Nasr was reported missing.

The other group -- which included almost all of those whose arrests are now being sought -- was in charge of the kidnapping operation itself, according to court documents.

On Feb. 17, shortly after noon, Nasr walked down the Via Guerzoni toward a mosque to attend daily prayers. He was being watched by a crew of eight operatives, who accosted him on the sidewalk, sprayed chemicals in his face and shoved him into the back of a white van, according to an eyewitness statement given to investigators.

The Americans, who between them were carrying 17 cell phones, immediately started dialing numbers in Italy and the United States, according to investigators, who reported that by piecing together records of those phones' electronic signals they were able to trace the route of the van as it headed toward Aviano Air Base, a joint U.S.-Italian military installation.

The van entered the base without being stopped at the regular security checkpoints, Milan investigators found. Court documents show that a U.S. colonel at the air base in charge of security received three phone calls from the operatives as they drove toward Aviano.

Milan prosecutors said they would ask the U.S. government for permission to interrogate the colonel, concluding that "it reasonably appears that he was involved with the execution of this kidnapping and safekeeping of the hostage." The colonel now works at the Pentagon, according to a report Saturday in Corriere della Sera, an Italian newspaper.

A few hours after his arrival at Aviano, Nasr was put aboard a Learjet and taken to Ramstein Air Base, a U.S. military installation in Germany. There, he was transferred to another plane, which flew him to Cairo, Italian court records show.

Most of the CIA operatives apparently did not accompany Nasr on his flights. Hotel records show that all but one of the Americans allegedly involved in the abduction stayed in Italy for a few days afterward. Four of them checked into luxury hotels in Venice. Two others spent a couple of days in the Italian Alps before leaving the country.

Milan investigators determined, however, that the operative they described as the leader and organizer of the kidnapping -- a CIA officer based in Milan whose identity was well known to Italian counterterrorism officials -- showed up in Cairo five days after Nasr disappeared, according to the court records.

One remaining mystery in the case is whether Italian intelligence officials knew about the operation beforehand.

Opposition politicians in Rome have asked the parliamentary intelligence oversight committee to question Interior Minister Giuseppe Pisanu and Defense Minister Antonio Martino about whether they were aware of and had approved the operation, known in CIA parlance as an "extraordinary rendition." Cases that have come to light in the past have generally proceeded with the cooperation of local officials.

Marco Minniti, a member of the Democratic Left opposition party, said the request was made "to ascertain if members of Italian intelligence participated in the operation and, if so, what role they had."

Paolo Cento, a Green Party member, said: "The alternatives are only two. Either our authorities knew, or the American 007s had full freedom of action on our territory."