A key government witness is expected to take the stand Tuesday in the trial of four men suspected of running a sleeper terrorist cell in metro Detroit.

Yousef Hmimssa is expected to testify against Karim Koubriti, Ahmed Hannan, Farouk Ali-Haimoud and Abdel-Ilah Elmardoudi, The four men are charged with conspiracy to support terrorism.

Hmimssa, a key witness for the prosecution, reached a plea agreement with the government, Local 4 reported. Details of the deal are expected to be released when he takes the stand, according to reports.

Prosecutors believe the four suspects were organizing a terror plot, and sending money overseas to support terrorist activity, Local 4 reported.

Hmimssa is expected to testify that the men were plotting attacks at popular vacation spots such as Walt Disney World and Las Vegas, Local 4 reported.

Defense attorneys argued to the Detroit federal courtroom that the men came to the United States to live the American dream, but ended up in the wrong place at the wrong time.

FBI Special Agent Mary Ann Manescu told the courtroom on March 31 that drawings of airplanes immediately caught her attention as she flipped through a day planner found in a Detroit apartment raid following the Sept. 11, 2001, terrorist attacks where three of the four men lived. She added that the day planner also contained a sketch that the government claims illustrates planes, a runway and a bunker at a United States air base.

Defense attorneys said the day planner belonged to a former occupant of the home who was mentally ill and had committed suicide. They argued that the prosecution's witness is a career criminal looking for an early release from prison.

A jury of 12 women and four men will determine if the evidence links the suspects to involvement in a terrorist plot.

It's the first trial in the United States for an alleged terror cell detected after the Sept. 11, 2001, terrorist attacks.