The first substantive hearing in the US war crimes tribunal at Guantanamo began on Thursday, since US President Barack Obama took office in January 2009.
Hearings began to determine whether US forces tortured a confession from Omar Khadr, a Canadian accused of murdering an American soldier in Afghanistan.
FBI agent Robert Fuller's testified that the interview with Khadr was comfortable and friendly once the hood and handcuffs were removed.
A sworn statement by Khadr will be reviewed by a US military judge.
In the statement, Khadr says he was forced to give false confessions, after being severely abused and humiliated by the US army.