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Four men accused of acting as a terrorist cell (search) covered their tracks by speaking in code as they conspired to bring about attacks in the United States and abroad, a federal prosecutor said in closing arguments Monday.

"If you put the pieces that we have together you'll see the picture," Assistant U.S. Attorney Richard Convertino said. "This is a terrorist cell."

The defendants took pains to cover their plans by using code and having people with mental problems sign documents, Convertino said. He told jurors the case was part of the government's effort to protect American lives.

"This is a case of great importance," Convertino said. "Don't give them another chance to make their plan effective."

Monday's closing arguments followed nearly two months of testimony in the federal trial, the first in the United States for an alleged terror cell detected following the Sept. 11, 2001, attacks. Closing arguments from defense lawyers, which were to begin in the afternoon, could stretch into Tuesday.

The defense was expected to attack the credibility of the government's star witness, a self-described scam artist who in five days of testimony described the defendants as Islamic extremists (search) who wanted to see Las Vegas and Disneyland destroyed, ship arms to the Middle East and smuggle "brothers" into the country.

Youssef Hmimssa testified that Abdel-Ilah Elmardoudi, who the government says led the terrorist "sleeper" cell, told him about the possibility of massive attacks on the United States one month before the jetliner hijackings of Sept. 11.

"This place is going to be just like Gaza Strip (search) and West Bank (search)," Hmimssa recalled Elmardoudi saying.

Hmimssa also testified that the men wanted him to make fake airport and FBI identification and that defendant Karim Koubriti wanted a license to haul hazardous materials.

The defense has portrayed Hmimssa as a liar who testified to save himself from harsher punishment.

Elmardoudi, Koubriti, Ahmed Hannan and Farouk Ali-Haimoud are charged with conspiracy to provide material support or resources to terrorists. The case stems from a raid six days after the Sept. 11 attacks that led to the arrest of Koubriti, Hannan and Ali-Haimoud. Elmardoudi, 37, was arrested in November.

The raid turned up much of the evidence in the case: false documents, a series of Arabic audio tapes, a video the government says cases possible targets and a day planner that contains what prosecution witnesses describe as sketches of an American air base in Turkey and a military hospital in Jordan.

The defense has dismissed the video as an innocuous travelogue. They claim the men found the planner, which belonged to a mentally ill man who died in an apparent suicide in March 2001.

Hmimssa, a Moroccan in the United States illegally, is himself awaiting sentencing after pleading guilty to fraud-related charges in three states. He has admitted using aliases, engaging in document fraud and leading a credit card scheme that netted more than $180,000.

One defense witness described him as wanting to use his testimony to exact revenge.

"This is a human being who has never told the truth in his life, who has made his living lying," Elmardoudi attorney William Swor told the jury during opening statements in March.

None of the defendants, who are from Morocco with the exception of the Algerian Ali-Haimoud, took the stand in the trial.

They face 15 years in prison if convicted of the terrorism count and five years in prison on another conspiracy charge. Koubriti, 24, Hannan, 34, and Ali-Haimoud, 22, also face two other fraud-related charges that carry penalties of up to 25 years in prison.