Miami — One of seven indigent men charged with plotting to blow up the Sears Tower in Chicago as part of an Islamic jihad was acquitted on Thursday, and a mistrial was declared in the prosecution of the six others after the jury said it was hopelessly deadlocked.
The outcome was a significant defeat for the Bush administration, which had described the case as a major crackdown on homegrown terrorists.
Officials had acknowledged that the defendants, known as the Liberty City Seven for the depressed section of Miami where they frequently gathered in a rundown warehouse, had never acquired weapons or equipment and had posed no immediate threat. But, the officials said, the case underscored a need for pre-emptive terrorism prosecutions.
In acquitting Lyglenson Lemorin, 32, a Haitian immigrant who was cast by the prosecution as a junior foot soldier in the group, the jurors were compelled by evidence that suggested he had tried "to distance himself" from the others, Jeffrey Agron, the jury foreman, said outside the courthouse.
Mr. Lemorin had split with the group's leader, Narseal Batiste, 33, and moved to Atlanta months before the seven were arrested last year, according to The Associated Press.
As for the six defendants on whom the jury deadlocked, the United States attorney's office here said Thursday that it would retry them. The judge, Joan A. Lenard, ordered jury selection for the retrial to begin Jan. 7 and barred prosecution and defense lawyers from discussing Thursday's outcome with reporters.
The defendants — five Americans and two Haitians — worked in a small construction business owned by Mr. Batiste and were members of the Moorish Science Temple, a sect that blends Islam, Christianity and Judaism and does not recognize the authority of the United States government. They were charged with planning to join forces with Al Qaeda to blow up the Chicago skyscraper and several federal buildings in an effort at a government overthrow.
The seven came under government surveillance in the fall of 2005 when a Yemeni man contacted the Federal Bureau of Investigation to report what he described as suspicious activity by them and their request that he help them contact Al Qaeda.
Mr. Agron, the jury foreman, who described himself as an educator at a synagogue, said the case's complexity, with seven defendants each facing four conspiracy counts, had made for "tough" deliberations.
"There were just different takes by different people," he said. "People have different takes on what they saw, on what was said and what was meant."
Mr. Agron declined to detail how the 12 jurors had split on each count and each defendant. But he said they had thought the weakest count was the government's charge that the defendants had conspired to wage war against the United States.
The other charges were conspiracy to provide material support to Al Qaeda, conspiracy to destroy federal buildings and conspiracy to provide material support for the destruction of federal buildings.
Each defendant faced up to 70 years in prison if convicted on all four charges.
The case first seemed headed for a mistrial on Thursday of last week, when the jury, in a note to Judge Lenard, suggested that it was struggling to agree on verdicts for all seven defendants. A second, similar note was sent to the judge on Monday. Both times, she directed the jurors to keep trying.
On Thursday afternoon, the jury sent out a third note, saying that it had reached a verdict on one defendant but that "we believe no further progress can be made."