Zacarias Moussaoui's indictment this week for conspiracy to commit murder is the first big catch in the post-Sept. 11 dragnet of Middle Eastern men, but other indictments handed down so far link no one else directly to any terrorist plot.
That's not to say such links may ultimately emerge, even as criminal proceedings on lesser charges - such as falsifying identification or bank fraud - go forward. And Attorney General John Ashcroft insists the government's "deliberate campaign of arrest and detention" has disrupted Al Qaeda's terror network inside the United States and may have thwarted other attacks.
But indicting so many people on minor charges - most of whom apparently played no role in plotting terror attacks - is a tactic being hotly debated in legal circles. Critics say most of those indicted - and others held on immigration violations - should not be held for months for such small-time offenses.
Still, experience suggests that complex terrorism investigations, which can take years to build, often rely on indictments unrelated to the terrorist attack itself.
"The Department of Justice is looking for any way it can to hold onto other individuals who may be tangentially involved in the events of Sept. 11," says former federal prosecutor Jan Handzik.
Mr. Ashcroft disclosed last month that about 500 people remain in custody, either as material witnesses or because of alleged immigration violation.
In addition, federal grand juries in at least 20 states have indicted another 105 individuals on charges such as bank fraud, forging housing-subsidy checks, or misusing Social Security numbers. Many of those indicted may simply be criminals swept up by the terror probe. Two men in New Jersey, for example, were indicted for conspiring to buy, receive, and possess $40,000 worth of stolen Kellogg's breakfast cereal.
Some of the alleged crimes, however, may have been committed "as preludes to the commission of a terrorist incident," says Brent Smith, a professor at the University of Alabama at Birmingham who has studied 2,700 criminal counts filed over the years against suspected terrorists.
This time, however, prosecutors are having to focus their fire on finding secondary figures - those who helped train or fund the hijackers. The primary culprits either died in the attacks or, if captured overseas, will probably face trials before military tribunals.
The single exception so far is Mr. Moussaoui, the alleged 20th hijacker who was detained in August on immigration charges. He is now charged with conspiring to commit an act of terrorism.
So far, judges who have been heard evidence in the cases of the more tangential defendants seem less than impressed. US district court Judge Shira Scheindlin in New York, for one, last month ordered that Osama Awadallah, a California college student accused of lying about knowing two of the hijackers, be released on bail.
In her opinion, the judge wrote: "It must be remembered that this defendant is charged with making false declarations - not with terrorism, or aiding and abetting terrorism, or conspiring with terrorists."
On Wednesday, the Associated Press reported that authorities now doubt that two other detainees - Indian nationals pulled off a train in Texas the day after the attacks - were involved. The two have been held as material witnesses and remain jailed in New York.