Alan Gershel, a senior prosecutor in the United States attorney's office there, wrote that the authorities could have problems proving the fraud case, that the money involved was relatively little, that it would appear "vindictive" and that the F.B.I. believed it "will actually have a significant negative consequence" by potentially harming relationships with Detroit's large Muslim population.

Such sane advice failed to carry the day in a Department more obsessed with its image than with justice. The face-saving strategy, revealed in the emails, was to push the defendants into a quick plea and deportation. The strategy worked with regard to one defendant, who agreed to plead guilty and be deported.

[Richard M. Helfrick, an assistant public defender representing the other defendant, Karim Koubriti,] said the Justice Department's internal debate confirmed his suspicions that prosecutors pursued the fraud case only after the collapse of the terror case became a political embarrassment. "This isn't a case that ordinarily would even have been brought," or would have been handled through a pretrial diversion program, he said.

The improper charging of a weak case was compounded by the Department's failure to disclose its own concerns about the flaws in its case.

Abraham Abramovsky, a law professor at Fordham University who has studied discovery rules, said the issue was a "gray area" because the e-mail communications discussed evidentiary issues that could conceivably factor into the guilt or innocence of the defendants.