When Jose Padilla was taken into custody at Chicago's O'Hare airport in 2002, government officials announced with great fanfare that he was plotting with Al Qaeda to detonate a radiological "dirty bomb" in a major US city.

Now, five years later, Mr. Padilla is about to stand trial in federal court here. But there is no mention of a dirty bomb plot anywhere in the case.

It is not an oversight. A criminal trial is not intended to be a history lesson. Instead, to protect Padilla's right to a fair trial, the case against him is based on a much more skimpy presentation of evidence.

The omission illustrates a fundamental tension between the Bush administration's iron-fisted approach to intelligence gathering in the war on terror and a US citizen's entitlement to constitutional and other protections of the criminal-justice system.

The alleged dirty-bomb plot was uncovered through the use of coercive interrogation tactics – torture according to Padilla and others – which renders the information too unreliable to be admitted in an American court. As a result, federal prosecutors were forced to build their Miami conspiracy case using evidence obtained through noncoercive means and investigative methods that did not violate core constitutional guarantees.

Barring the dirty bomb and other improperly obtained evidence from the criminal case has greatly complicated prosecution efforts to win a conviction and potentially put Padilla behind bars for the rest of his life.

But at the same time, defense lawyers are worried that their client's pretrial notoriety as the Al Qaeda "Dirty Bomber" could make it impossible for Padilla to receive a fair trial.

US District Judge Marcia Cooke is expected to press hard this week to try to find 12 jurors and six alternates who have never heard of Padilla, or who are able to put any knowledge of the dirty bomb allegations aside and base their deliberations solely on the evidence and testimony presented in the courtroom.

Conspiracy case with no specific plot

Unlike most terror-conspiracy cases, the case against Padilla and his two co-defendants does not focus on any particular plot or attack. Instead, prosecutors say the defendants violated US law by participating in a North American support cell that sent money and recruits to a wide variety of radical Muslim groups overseas. It is the overseas Muslim groups that engaged in violent jihad, or holy war.

Padilla's part in the alleged conspiracy, prosecutors say, is that he became a willing recruit who traveled to the Middle East and Afghanistan, where he signed up for military training with Al Qaeda.

Padilla's lawyers tell a different story. They say their client is a Muslim convert from south Florida who traveled to the Mideast to further his study of Islam. He has an Egyptian wife, whom he met while a student in Cairo, and two small children.

Another defendant – the alleged leader of the support cell – is Adham Amin Hassoun, a Palestinian who fled Lebanon as a refugee in the 1980s and settled in south Florida. He has suggested in the past that he was targeted for investigation after the 9/11 attacks because of his outspoken political beliefs.

The third defendant, Kifah Wael Jayyousi, founded and ran several humanitarian organizations that allegedly contributed money to suspected terror groups. He also produced "The Islam Report," a publication that prosecutors say promoted violent jihad as a religious obligation.

The defendants deny that they supported violence. They say that they were helping fellow Muslims in need.

According to the indictment, the North American support cell was active for about eight years from October 1993 to November 2001. During that period, $58,700 was allegedly sent overseas to various Muslims. In its most active year – 1998 – the group transferred $19,800 to Egypt and Kosovo.

In November 2001, three weeks after the 9/11 attacks, a $2,000 check was issued for "Afghan relief."

Although the indictment tracks the movement of money, it does not identify how the money was spent. Prosecutors say Mr. Hassoun and others used coded language to disguise their support for terror operations. For example, some checks were designated to support "tourism," another noted simply "for brothers."

But other checks suggest there was no attempt to conceal the destination of the money. Some checks were marked "Chechnya," "Kosovo," and "Somalia." One included the notation: "one for Bosnia one for Libya."

Prosecutors say coded language was also used in thousands of conversations secretly monitored and recorded by US intelligence officials acting under the Foreign Intelligence Surveillance Act. In February 1998, Hassoun was recorded discussing that $3,500 sent to Lebanon had been used to purchase "zucchini."

One of the strongest pieces of evidence in the case against Padilla is a "Mujahideen Data Form" that Padilla allegedly filled out in July 2000 before attending an Al Qaeda training camp in Afghanistan.

Key document from unknown Afghan

Padilla's lawyers are raising questions about the document. They say it was delivered to the government by an anonymous Afghan citizen who drove up to a Central Intelligence Agency officer in December 2001 and handed him a number of documents that the Afghani said were recovered from an abandoned house once occupied by "Arabs."

According to a forensic expert for the defense, the data form was filled out using two different kinds of ink that are typically not found outside North America. The form was completed at different times with three different types of handwriting, according to the defense expert.

The suggestion is that someone else might have signed Padilla's name or somehow tampered with the form to help shore up the government's case.

Prosecutors dispute such allegations. They say they will call the CIA officer to testify. But they refuse to reveal his identity to defense lawyers. And in a highly unusual request, they've asked the judge to allow the CIA officer to don a "light disguise" while on the witness stand.

"This witness has been working for the CIA since 1991. The government has a duty to protect his identity," Assistant US Attorney Stephanie Pell told Judge Cooke in a recent pretrial hearing.

Padilla's lawyers disagreed. "For us to do our job, we have to know who this person is. We have to investigate," said Assistant Federal Public Defender Orlando do Campo. "We oppose the disguise. It is silly and disrespectful of this court."