Oh, spare me. Barack Obama has explicitly targeted, and killed, American citizens in drone attacks, something even Bush never did. This is public knowledge. I count myself a hawk in matters of Islamic terrorism, but I am also a libertarian and this is beyond the pale. There has to be a bright line in these killings, and American citizens must never be targeted for execution by some politician just because they think they should be dead. This is why we have courts and due process. Suddenly however, all the people who were so deeply, deeply, concerned about waterboarding have been silent about US citizens being eliminated on presidential orders.
As for your claim, evidence? He did no such thing, because he knew that as soon as the prisoners were released most would go right back to killing again (or do you think that they were mostly innocent?), as indeed several who were released already have. Even his Mainstream Media toadies wouldn't be able to cover that up.
Instead we have seen a massive gunrunning operation intended to give weapons to Mexican drug cartels, conducted by Eric Holder, Obama's chief law enforcement officer, that has resulted in the murder of four innocent Americans and who knows how many Mexicans. The legal term for this is "accessory to murder". Holder has perjured himself before Congress on this and Obama and his media has done nothing but support him. What is your stand on that?
Obviously they were innocent by the very definition of it in the US system: innocent until proven guilty. Obviously if we could prove them guilty we wouldn't need Gitmo, we'd try them in criminal court. We didn't because we had nothing on them.
Also, your "went back to killing" is an assumption. How do you know they were killing before? I would expect that, once released, the people who were illegally kidnapped would seek some action against those that destroyed their lives and held them against their will for years.