The US prison facility at Guatanamo Bay continues to be a thorny problem. Almost two thirds of Americans surveyed recently opposed closing the prison there. That's despite allegations of torture, the facility continuing to provide fuel for jihadi nutcases and suicide bombers and Barak Obama's promise to close the facility.
Those being detained at Guantanamo Bay are not going to be charged with any crime. For many, there's no evidence other than hearsay reports. Others have been tortured and their trials would reveal just to what extent. There's also the small problem that some of those detained and subsequently release have gone on to become involved in terrorism.
People detained for five years, tortured, never charged let alone convicted of a crime, held in solitary confinement, subjected to routine humiliation, unable to see their families, etc. may go home, get a job, keep a low profile. Or they may write a book about what they've been through. Or they may find they actually have a reason to be pissed off with the United States military and a government that allowed (or, if you like, encouraged) it all to happen.
Guantanamo will cease to be a problem for the US when it's closed. If they've not got enough evidence to charge the people there, they should let them go. And expect law suits to follow.