Federal prosecutors in Chicago, preparing for the first criminal trial of a Muslim charitable activist since Sept. 11, 2001, on terrorism-related charges, have assembled 102 pages of powerful allegations about his foundation's intimate links with al Qaeda and various extremist movements over the past 15 years.

The activist, Enaam Arnaout, head of the Benevolence International Foundation, was once Osama bin Laden's chauffeur, according to the prosecutors' account. The government says he also helped funnel money and equipment to al Qaeda operatives on three continents and provided cover for top bin Laden aides who were trying to build chemical and nuclear weapons -- all while posing as the director of a charity that aids needy Muslims.

The document reads like a spy novel, describing Arnaout and a small group of activists funded by a wealthy Saudi businessman as they follow al Qaeda fighters around the world, from one encampment and war zone to the next. From Pakistan and Afghanistan to Sudan, where bin Laden lived in the early 1990s, and then to Bosnia, Chechnya and Azerbaijan, Arnaout provided money, guns, medical supplies and an array of services to al Qaeda and local holy warriors closely affiliated with the terrorism network, prosecutors contend.

But there is one problem for prosecutor Patrick J. Fitzgerald, a terrorism expert and the U.S. attorney in Chicago, who is set to try the case that begins tomorrow: The federal judge hearing the matter may prohibit prosecutors from using some of the most damaging evidence in court.

U.S. District Judge Suzanne B. Conlon all but threw out the government's document, saying prosecutors had failed under the rules of evidence to show why any of the assertions in the document should be brought before the jury.

Her sealed decision was made public late Wednesday. Arnaout's lawyers and the U.S. attorney's office in Chicago declined to comment on the case.

"The government's case is crumbling," said one lawyer sympathetic to the defense. "Clearly, the judge is angry at the government." But sources familiar with the thinking of Justice Department officials said prosecutors are looking for ways to introduce evidence that the judge has said she might exclude.

The government has made cracking down on Muslim charities a cornerstone of its war on terror and is eager to win its first high-stakes trial involving al Qaeda funding.

In a seven-count indictment filed last October, the government accused Arnaout, 40, a naturalized U.S. citizen from Syria, of crimes that include money laundering, wire fraud and conspiracy to provide material support to terrorists. The indictment says that Arnaout, bin Laden and top al Qaeda officials began working closely together in the late 1980s, when they all fought the Soviets in Afghanistan.

Arnaout's attorneys deny the charges, saying that Benevolence is a humanitarian group and that the prosecutors have misconstrued innocent events. They say it is unfair for the government to portray Arnaout's support for the anti-Soviet Afghan mujaheddin in the 1980s as criminal, because the United States covertly aided that struggle.

Conlon's ruling came in response to a "proffer" -- a list of assertions the prosecutors plan to make at trial -- filed Jan. 6. It outlined the incriminating statements made by Arnaout's alleged co-conspirators in al Qaeda, Benevolence and related groups.

The proffer was designed to lay out the array of co-conspirators' written or spoken statements that the government intended to introduce at trial. The idea was to streamline the trial by having the judge admit all the material beforehand.

Under the law, hearsay -- information provided by a witness who describes what he or she claims other people said -- is inadmissible. But one exception to the rule covers statements made by one co-conspirator and described by another member of the conspiracy.

It is rare for a judge to reject an entire proffer centered on hearsay issues, but it is clear from her ruling and remarks from the bench that Conlon found major flaws in the prosecutors' case, legal sources said.

On Monday, she ruled that none of the evidence in the proffer was admissible, suggesting in her decision that it was too anecdotal and failed to designate which statements from which co-conspirators should be excepted from the hearsay rule.

"The proffer is devoid of analysis linking proffered hearsay to a specific conspiracy," she wrote. The authors of many statements and documents "are not always identified," she added. "Dates often cannot be discerned from documents." Prosecutors were too imprecise in treating Arnaout's actions in 1988 as part of a sprawling conspiracy extending to the present, she said.

"Given the insufficiency of the . . . proffer, the court cannot find by a preponderance of the evidence that the proffered statements are admissible under the co-conspirator exception to the hearsay rule."

Now prosecutors must find a different exception to the hearsay rule that would allow introduction of the mass of evidence -- and legal experts said there are few available -- or they must win over Conlon one piece of evidence at a time. People who know Conlon, an appointee of President Ronald Reagan, say that may be difficult.

In addition, prosecutors have provisionally agreed, with little explanation, not to introduce any documents seized by police at Benevolence's offices in Bosnia last year. The decision removes many telling documents from the case, and prosecutors apparently took the step under pressure from the judge, who has expressed discomfort about the vagueness of the dates, authorship and authentication of many documents.

One of the documents seized in Bosnia describes a letter Arnaout wrote in 1994 to an al Qaeda member on behalf of bin Laden. "He [bin Laden] is far away from me and authorized me through a communication to sign on his behalf," Arnaout wrote, according to prosecutors. Prosecutors contend that in another document written by Arnaout, this one undated, he called the al Qaeda leader "the exalted Osama bin Laden."

It is unclear how the judge will treat the remainder of the government's case, which rests on papers, computer files and photographs seized by agents at Benevolence's suburban Chicago offices and other sites, as well as testimony from at least two former al Qaeda members. One is Jamal Ahmed al-Fadl, whose testimony helped convict several former al Qaeda members for the 1998 bombings of two U.S. embassies in East Africa.

Between 1993 and 1995, bin Laden told al-Fadl repeatedly that al Qaeda was using Benevolence to move funds around the world, the government contends. Al-Fadl also will testify that bin Laden and other al Qaeda leaders stated that Benevolence funneled some of its funds to the terrorist network while claiming to spend all its money building mosques and helping the poor.

An undated internal report of the group, seized from Benevolence's Illinois offices, said of its activities in the Sudan: "From its first day, BIF aimed to support jihad and mujaheddin by assisting in military and logistical support."

The government also said that in 1998 and 1999, Saif-ul-Islam, one of al Qaeda's top military commanders, worked as a Benevolence official in Chechnya. In 1998, Benevolence provided another top al Qaeda operative, Mamdouh Salim, with documents signed by Arnaout that falsely identified Salim as a Benevolence director, a cover story he used on a trip to Bosnia, prosecutors said. Salim, who is facing trial in the East Africa bombing case, has been convicted of stabbing a New York prison guard in the eye, causing permanent brain damage.

The trial for Enaam Arnaout, head of the Benevolence International Foundation, begins tomorrow.