Italian authorities suspect the Egyptian was the target of a CIA-sponsored operation known as rendition, in which terrorism suspects are forcibly taken for interrogation to countries where torture is practiced.

The Italian probe is one of three official investigations that have surfaced in the past year into renditions believed to have taken place in Western Europe. Although the CIA usually carries out the operations with the help or blessing of friendly local intelligence agencies, law enforcement authorities in Italy, Germany and Sweden are examining whether U.S. agents may have broken local laws by detaining terrorist suspects on European soil and subjecting them to abuse or maltreatment.

The CIA has kept details of rendition cases a closely guarded secret, but has defended the controversial practice as an effective and legal way to prevent terrorism. Intelligence officials have testified that they have relied on the tactic with greater frequency since the Sept. 11, 2001, attacks.

The Bush administration has received backing for renditions from governments that have been criticized for their human rights records, including Egypt, Jordan and Pakistan, where many of the suspects are taken for interrogation. But the administration is getting a much different reception in Europe, where lawmakers and prosecutors are questioning whether the practice is a blatant violation of local sovereignty and human rights.

There are many practical and legal hurdles to filing criminal charges against U.S. agents, including the question of whether they are protected by diplomatic immunity and the matter of determining their identity. However, prosecutors in Italy and Germany have not ruled out criminal charges. At the same time, the European investigations are producing new revelations about the suspected U.S. involvement in the disappearances of four men, not including the Egyptian, each of whom claims they were physically abused and later tortured.

In Germany, a 41-year-old man, Khaled Masri, has told authorities that he was locked up during a vacation in the Balkans and flown to Kabul, Afghanistan, in January 2004, where he was held as a suspected terrorist for four months. He said that only after his captors realized he was not the al Qaeda suspect they were looking for did they take him back to the Balkans and dump him on a hillside along the Albanian border. He recalled his captors spoke English with an American accent.

German prosecutors, after several months of scrutinizing his account, have confirmed several key parts of his story and are investigating it as a kidnapping.

"So far, I've seen no sign that what he's saying is incorrect. Many, many pieces of the puzzle have checked out," said Martin Hofmann, a Munich-based prosecutor overseeing the investigation. "I have to try to find out who held him, who tortured or abused him, and who is responsible for this."

In Sweden, a parliamentary investigation has found that CIA agents wearing hoods orchestrated the forced removal in December 2001 of two Egyptian nationals on a U.S.-registered airplane to Cairo, where the men claimed they were tortured in prison.

One of the men was later exonerated as a terrorism suspect by Egyptian police, while the other remains in prison there. Details of the secret operation have shocked many in Sweden, a leading proponent of human rights.

Although Swedish authorities had secretly invited the CIA to assist in the operation, the disclosures prompted the director of Sweden's security police last week to promise that his agency would never let foreign agents take charge of such a case again.

"In the future we will use Swedish laws, Swedish measures of force and Swedish military aviation when deporting terrorists," Klas Bergenstrand, the security police chief, told reporters. "That way we get full control over the whole situation."

Clues to a Mystery

In Milan, the Egyptian-born cleric attracted the attention of counterterrorism police soon after arriving in Italy in 1997 from Albania. Known as Abu Omar, his full name was Hassan Mustafa Osama Nasr. He was 42, a veteran fighter from the wars in Bosnia and Afghanistan and a wanted man in Egypt, where authorities had charged him with belonging to an outlawed Islamic radical group.

Nasr frequently preached at two mosques in Milan that have long attracted religious and political extremists, according to Italian and U.S. officials. One of the mosques, a converted garage on Viale Jenner, is classified as a financier of terrorism causes by the U.S. Treasury Department, which has accused it of supporting "the movement of weapons, men and money around the world."

Nasr reinforced the mosque's reputation by preaching angrily against the U.S.-led invasion of Afghanistan and handing out vitriolic pamphlets criticizing U.S. policy in the Middle East. Italian counterterrorism police tapped his home telephone and kept him under surveillance.

"He was the kind of person who, let's put it this way, did not speak diplomatically," said Abdelhamid Shaari, president of the Islamic Cultural Center at Viale Jenner, who denies that either the mosque or the center sponsor terrorism or illegal activity. "When he attacked America, he did not speak in half-measures. He got right to the point."

When Nasr vanished, his family and mosque leaders reported it as a kidnapping, after a witness said she saw the abduction. The witness, a recent immigrant, said she was scared to repeat her story to the police, however, leading some investigators to speculate that Nasr had disappeared on his own and gone to Iraq to fight U.S. forces.

Italian police opened a missing person investigation, but the case stalled for more than a year. That changed in April 2004, when Nasr's wife unexpectedly received a telephone call from her husband. He told her he had been kidnapped and taken to a U.S. air base in Italy. He said he was then flown to another U.S. base, before being taken to Cairo.

The call was recorded by Italian police, who had kept the wiretap on Nasr's home telephone in place. Although transcripts have not been made public, Nasr's colleagues at the mosque said he reported that he had been tortured and kept naked in subfreezing temperatures in a prison in Cairo.

During the phone call, Nasr told his wife that he had been let out of prison in Egypt but remained under house arrest. His relatives have said they believe he was imprisoned again shortly afterward when news of the recorded conversation was reported by Italian newspapers.

The existence of the wiretap is revealed in sealed Italian court papers reviewed by The Washington Post. The documents, dated in the spring of 2004, include a judge's authorization to continue the wiretap and show that investigators were pursuing the theory that covert agents -- possibly from the United States, Italy or Egypt -- were behind the kidnapping.

Italian investigators have since determined that 15 agents, some of them CIA operatives, were involved in Nasr's abduction, according to reports in Corriere della Sera, a leading Italian daily. Investigators were able to trace calls made by the agents by linking calls made by the same phones near the mosque and Aviano Air Base on the day Nasr vanished, the newspaper reported.

The investigation is being led by Armando Spataro, a well-known counterterrorism prosecutor whose office has also built a hard-nosed reputation for winning convictions in cases involving the Mafia and political corruption. Spataro, who has worked closely with U.S. officials in the past on terrorism cases, confirmed that he visited Aviano last month but declined to comment further.

Capt. Eric Elliott, a U.S. military spokesman at Aviano, said Spataro met at the base for several hours with Italian military officials, who then forwarded a request for records to their American counterparts. Elliott declined to describe the records being sought, citing "an active investigation."

The U.S. Embassy in Rome declined to answer questions about whether American agents were involved in Nasr's disappearance. "We do not comment on intelligence matters," said Ben Duffy, an embassy spokesman.

Italian opposition lawmakers have demanded answers from Prime Minister Silvio Berlusconi's government on whether Italian agents or intelligence services played a role. But government ministers have remained tight-lipped.

Shaari, the director of the Islamic cultural center in Milan, said some Muslims are worried they could be kidnapped, too.

"If they can take Abu Omar, then they can take anyone," he said. "This is an extremely dangerous precedent, both for the Muslim community and for Italy, as a democratic and free state."

Claims Corroborated

In late December 2003, Khaled Masri got into a bitter argument with his wife in their home town of Ulm, Germany. They agreed he should get away for a few days, so he bought a bus ticket for Skopje, Macedonia.

At the Macedonian border on New Year's Eve, immigration officials took a close look at his passport and detained him, without explanation. Other agents later interrogated him and pressed him to admit he was a member of al Qaeda, according to accounts Masri gave his attorney and German prosecutors.

Masri protested his innocence, but was kept under guard in Macedonia for three weeks. He said that one day in late January 2004, he was beaten, stripped, shackled and put on a plane that took him to Afghanistan. There, he was kept in a cell under dismal conditions, deprived of water and repeatedly interrogated. Only after going on a hunger strike, he said, did his captors relent; he was flown back to the Balkans in May 2004.

He said he was released near an Albanian border checkpoint, where guards returned his passport and cash. By the time he made it home, even his wife was reluctant to believe his story, thinking he had left her for another woman, according to his attorney.

German police have questioned Masri several times and said they had found his version of events consistent and believable. Stamps in his passport show he entered Macedonia and left Albania on the dates he described. The bus driver on the route to Skopje confirmed to investigators that Masri had been on board and was taken away by border guards.

Investigators have conducted a chemical radioisotope analysis of Masri's hair. They said the findings backed up his story that he was malnourished while in captivity.

Flight logs also support Masri's claim that he was flown out of Macedonia by U.S. secret agents. Aviation records show a U.S.-registered Boeing jet arrived in Skopje at 9 p.m. on Jan. 23, 2004, and departed about six hours later. Masri had provided German investigators with the same time and date.

The flight plan shows the aircraft was scheduled to go to Kabul, but later amended its route to include a stopover in Baghdad. The existence of the flight logs was first reported by Frontal 21, a news show on the German television network ZDF. A copy of the logs was obtained by The Washington Post.

The jet, with tail number N313P, was registered at the time to a U.S. firm, Premier Executive Transport Services Inc., that records suggest is a CIA front company. The same firm owned another aircraft, a Gulfstream jet, that has been used in other rendition cases, including the one in Sweden.

Masri's attorney and investigators say they think he was abducted because his name is similar to that of an al Qaeda suspect, Khalid Masri, who allegedly played a crucial role in persuading the members of the Hamburg cell who carried out the Sept. 11 attacks to go to Afghanistan, where they first met Osama bin Laden.

Manfred Gnjidic, the lawyer, says he has asked the U.S. Embassy in Berlin for an explanation of what happened, but has received no response.

"We are quite sure that they were behind this," said Gnjidic. "We are looking for punishment and to hold someone accountable."

Robert Wood, an embassy spokesman, declined to answer specific questions about the case. "But our policy is pretty clear," he said. "The United States does not transfer detainees to countries where we believe it is more likely than not that they will be tortured."

Macedonian officials also had little to say. "Our answer is, no comment," said Goran Pavlovski, spokesman for the Macedonian Interior Ministry. "If the Germans want information, they should ask us about it, and we will respond."

Under German law, prosecutors have the authority to investigate any crime committed against a German citizen, even in foreign lands.

Hofmann, the Munich prosecutor, acknowledged that he has limited powers to investigate cases outside Germany. But he said he was preparing a formal request for legal help from the Macedonian government, as well as from Albanian and Afghan officials.

"I'm confident that other information will be forthcoming," he said. "This case has a considerable political meaning. There's a certain amount of pressure on everyone involved."

Staff researcher Julie Tate in Washington contributed to this report.

© 2005 The Washington Post Company