Regardless, I'm sure you remember a couple of years ago they arrested an American who had been working in Thailand after he confessed to murdering JonBenet Ramsey (that kid from the 5 year olds beauty pageants and stuff), except then it turned out he didn't actually do it. False confessions aren't always beaten out of people, from time to time they're made voluntarily. And they're made more often than you'd probably imagine as well.
Now I don't think these guys have made false confessions, I'm sure the prosecution have sufficient evidence to prove that they were responsible if their lawyers claim that (or at least I sure as hell hope they do, but if they don't then equally I'd hope they were found not guilty) Regardless of my position on their guilt, I still think they have to be tried like anyone else in order to make sure.