In a Feb. 7, 2002 memo, a partial reconstruction of the case by the Swedish security police noted that "the American side" had offered to help in the deportation "by lending a plane for the transport."
In addition, lawyers from the Swedish Justice Ministry wrote in a separate memo on April 12, 2002 that "the transport from Sweden to Egypt was carried out with the help of American authorities." Both documents were heavily redacted before their release.
A flight plan filed with Swedish aviation authorities shows that the Gulfstream jet was registered to a Massachusetts company, Premier Executive Transport Services. U.S. aviation records show that the firm has only two registered aircraft and that they have permits to land at U.S. military bases around the world.
Advocacy groups such as Human Rights Watch and Amnesty International have called on the U.N. High Commissioner for Human Rights to open an inquiry into the case.
"The only way to discover what the U.S. role was is through an international inquiry under the auspices of the U.N.," said Julia Hall, a lawyer for New York-based Human Rights Watch. "There's no transparency otherwise. We just don't know what buttons were being pressed by whom."
While Sweden has said it would welcome such an investigation, the United Nations is unlikely to act unless Egypt agrees to cooperate, human rights groups said. Egyptian authorities declined to comment on that possibility. But Hossan Salama, an official with the Egyptian state security service, denied that the United States was directly involved in the deportation.
"The Americans had absolutely nothing to do with this capture," he said in a brief interview. "It was something completely done with the Swedes."
As part of their agreement with the Egyptian government, Swedish diplomats insisted that they be allowed to visit Agiza and Zery in prison regularly to ensure that they were not mistreated.
Swedish officials did not schedule the first visit until more than a month after the men arrived in Egypt. They were not allowed to see them except in the presence of prison guards and were forced to rely on an interpreter provided by the Egyptian security services.
In a report made public shortly afterward, Sven Linder, the Swedish ambassador to Egypt, wrote that Agiza and Zery told him they had been treated "excellently" in prison and that to him "they seemed well-nourished and showed no external signs of physical abuse or such things."
Another section of the ambassador's report that remained classified until recently, however, offered a different appraisal. It noted that Agiza had complained that he was subjected to "excessive brutality" by the Swedish security police when he was seized and that he was repeatedly beaten in Egyptian prisons. Swedish diplomats in Cairo declined to comment on the case.
Agiza's parents and lawyers said in interviews that he was severely punished by his Egyptian captors after he complained to the Swedish officials and was warned to keep quiet during future visits.
"Torture is a systematic thing in these prisons," said Mohammed Zarai, director of the Human Rights Center for the Assistance of Prisoners in Cairo. "Every time when these people visited him, as soon as they left, he was beaten and tortured. They would ask him:. . . . Are they telling the Swedes to come visit?"
Agiza's mother, Hamida Shalaby, said he told her during separate visits that he was given electric shocks and that prison doctors tried to cover up scars on his body by applying a special cream. "He couldn't even pick up his arms to hug me," she said in an interview. "He was very slow and very tired and very weak."
Agiza's attorney in Stockholm has filed a complaint about the handling of his asylum case with the U.N. Committee Against Torture. Although the committee has no power to free him, it could rebuke Sweden for violating international conventions prohibiting torture if it determines that the Swedish government was liable for his alleged mistreatment by expelling him to Egypt.
"The Swedish government is facing a very hard situation now," said Hafez Abu-Seada, a Cairo lawyer who represented Agiza at his trial and serves as general secretary for the Egyptian Organization for Human Rights. "Their reputation as a leading human rights nation is at stake."
Zery's attorney in Stockholm has filed a similar complaint on his client's behalf with the European Court of Human Rights.
Zery was released from a Cairo prison in October but is not permitted to leave the country and remains under strict surveillance by Egyptian security forces.
In a brief telephone conversation last week, he said he was willing to grant an interview and invited a reporter to visit. He canceled the appointment an hour later, however, saying that an Egyptian security official had ordered him not to talk.
Staff researcher Margot Williams in Washington contributed to this report.