Federal prosecutor Richard Gregorie said the government plans to retry the six next year. The Bush administration had seized on the case to illustrate the dangers of homegrown terrorism and trumpet the government's post-Sept. 11 success in infiltrating and smashing terrorism plots in their earliest stages.
Lyglenson Lemorin was acquitted and buried his face in his hands when the verdict was read.
The jury gave up on the other defendants after nine days of deliberations on four terrorism-related conspiracy charges that carry a combined maximum of 70 years in prison. The jury twice sent notes to the judge indicating they could not reach verdicts but were told to keep trying. The mistrial came after their third note.
"We believe no further progress can be made," it said. U.S. District Judge Joan Lenard read the note in court.
Prosecutors said the "Liberty City Seven" - so-named because they operated out of a warehouse in Miami's blighted Liberty City section - swore allegiance to al Qaeda and hoped to forge an alliance to carry out bombings against America's tallest skyscraper, the FBI's Miami office and other federal buildings.
The group never actually made contact with al Qaeda. Instead, a paid FBI informant known as Brother Mohammed posed as an al Qaeda emissary.
The defense portrayed the seven men as hapless figures who were either manipulated and entrapped by the FBI or went along with the plot to con "Mohammed" out of $50,000.
The group never actually made contact with al Qaeda and never acquired any weapons or explosives. Prosecutors said no attack was imminent, acknowledging that the alleged terror cell was "more aspirational than operational."
But then-Attorney General Alberto Gonzales said after the arrests in mid-2006 that the group was emblematic of the "smaller, more loosely defined cells who are not affiliated with al Qaeda, but who are inspired by a violent jihadist message."
And U.S. Attorney R. Alexander Acosta of Miami said: "Our mission is to disrupt these cells if possible before they acquire the capability to implement their plans."
The Liberty City Seven, who included immigrants from Haiti and the Dominican Republic, adhered to a sect called the Moorish Science Temple that blends elements of Islam, Christianity and Judaism.
The government case was built largely on FBI surveillance video and some 12,000 telephone intercepts.
One key piece of evidence was a video of the seven men taking an oath of loyalty to al Qaeda and Osama bin Laden in a March 2006 ceremony.
Also, the group's leader, 33-year-old Narseal Batiste was overheard talking about starting a "full ground war" against the U.S. government by bringing down the 110-story Sears Tower - an attack he said would be "as good or greater than 9/11."
Batiste also supplied the informant with detailed wish lists that included assault rifles, bulletproof vests, uniforms, motorcycles and $50,000 in cash, prosecutors said.
However, Batiste testified he faked interest in the plot and really only wanted the money.
Members of the group also took reconnaissance photos of the FBI office and downtown federal buildings at the informant's request.
Defense lawyers contended that the informant and an overzealous FBI were responsible for pushing the alleged conspiracy along.
"This was all written, directed and produced by the FBI," said defense attorney Albert Levin.