There are a group of Federal Prosecutors and investigators who have become experts at convicting terrorists in the U.S. while not compromising national security. The Judges who hear these cases follow the law. The Marshals who manage these prisoners are extremely competent and well-trained.
I don't have a problem with Gitmo, enhanced interrogations, or electrocuting someone's testicles if it will save American lives. The mistake was trying to codify it--writing memos, trying to make it legal and on the books.
Regarding the story in the OP -- I had already heard this 1 in 5 stat. How many people total are we talking about? What was the circumstances of their release from Gitmo?