US attorneys said 19-year-old Mohammed Hamzah Khan, who was arrested last month at O’Hare International Airport in Chicago, was not just a misguided young man but one who had for some time planned to abandon his parents and join the terrorist group ISIS in Syria.

According to the attorneys, Khan got a job to pay for supplies and the plane tickets it would take to get not only himself but his then 17-year-old sister and 16-year-old brother to Turkey.

Attorneys said the three siblings would then make their way to an ISIS stronghold in Syria. They were stopped by border agents in Chicago.

Federal agents searched the family’s home and said they found letters from all three siblings explaining they were going to join jihadists and ISIS, and begged their parents not to call police.

In the letters, they said it was their duty to join those fighting for an Islamic state.

Prosecutors also said they found notebooks with Khan’s name in it that depicted ISIS flags and fighters. They presented web searches that they say are from Khan’s phone and included searches for suicide bombers.

Khan’s defense attorney, Tom Durkin, argued his client in an American citizen with deep but misguided religious beliefs who needs counseling, not jail, while he awaits trial.

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