That all said, it's still not right that these kids are detained for so long based on such circumstantial evidence (and that's overstating the weight of evidence, if these articles are to be believed verbatim) is a clear abuse of justice. Kids say stupid things. As adults we might cringe, but many of us were the same when we were teenagers. So locking someone up based on a stupid comment is complete unacceptable.
edit: just to clear up a few points because I think some have misunderstood me:
1) The comments in question were posted publicly on Facebook. It wasn't a PM - it was a public message. This is why I stated that the teenager in question likely wouldn't have made those comments in the same way in real life (ie he wouldn't stand in the middle of a busy town center and announce the same comments at the top of his voice for all to hear).
2) I appreciate the comments were a "joke" and it's not the content of the message that offended me (far from it - I have quite a dark sense of humour myself). It was the fact that he publicly announced his comments that I thought was stupid. You have no idea who might misunderstand public comments (case in point, me having to make clarifications in this post) - and this is particularly dangerous with darker jokes where others might -at best- be offended, but at worse, miss the point entirely. This isn't about censorship, it's about respecting your audience (ie keep the darker jokes private where your friends -who understand and share your humour- can enjoy).
3) I'm not blaming the teenager (or not exclusively anyway). I think what has happened to him is completely and utterly unacceptable. However I do think he was wrong for posting those comments to begin with. This is one of those instances where several parties are in the wrong.
I hope this clarifies a few things :)