Gitmo is full of really dangerous and nasty people who were most likely plotting to murder innocents for the cause of religious zealotry.
How dangerous does this man sound to you: http://en.wikipedia.org/wiki/Mamdouh_Habib
He was arrested on bullshit reasoning in Pakistan, tortured, locked in Gitmo for 3 years (despite supposedly being a terrorist and having inside knowledge of 9/11), and then released without charge. Government officials have admitted he had nothing to do with terrorism, yet nobody has been held accountable for that.
If these people are heinous criminals then give them their trial and be done with it already. Criminals still have rights, and that includes the right to have their side heard.