The US government say they have detained around a thousand people since September 16th. A few have been let out when the government was eventually sure they had nothing to do with the attacks — and of course this is the case for almost everyone held. They describe sitting in tiny cells by themselves in the cold with no clothes, being denied contact with either lawyers, family, or even fellow prisoners, and being called nothing but “fucking terrorist”.
These are mostly not people suspected in the attacks. These are simply people who they suspect might have had contact with people involved in the attacks at some point — for example, one of the first that they released was a former roommate of a person suspected.
Last week the FBI admitted that they'd gotten effectively no information from the people they're holding (not surprising if the people aren't involved), and that they were going to being torturing and drugging them (in violation of every human rights and war crimes code ever written) to try and get confessions (even though they admit that many of these people may not actually be connected to any crimes).
The inevitable has happened… they just executed their first prisoner. No matter what excuses as to the cause of death are made, there is NO explanation that can leave out “murdered by the US government”.