I have a sneaking suspicion that these kids were brainwashed.
Someone got to them online, probably on a pre-teen message board, and told them to kill their friend.
Dude, it was on reddit - the rapiest, child preadtoring, pedorific cum bucket to ever grace the planet. How that website is frequented by so many, I'll never understand.
If you don't know how it works, pretty much everything relies on up-voting. Things that get up-voted, stay, get bigger, and grow. So, you get odd sub-reddits (like our sub-forums) that people have shown they support. By odd I mean: pictures of dead kids, underage girls (r/jailbait), etc. No, I don't mean 'a picture' of dead kids, I mean an entire sub-section devoted to people looking at pictures of dead kids.
Anderson Cooper did a piece on /r/jailbait in 2011 that pretty much ended with it being shutdown, but for some reason the story never really caught more traction. After that sub-reddit was taken down, a new one just popped up. They don't ban the mods / contributors of these forums, they actually encourage them because they bring in so much traffic.
SomethingAwful.com did a huge piece spotlighting all the pieces of shit within reddit after the Cooper piece that helped get the original sub-forum closed. I'd link you the archive, but it's not able to be viewed by non-members.
Here's another link to a different forum citing what happened in that time:
http://teaminterrobang.com/archive/index.php?t-37648.html
Anyway, like I said, since then, it's only gotten bigger, not smaller. I know this is kind of a long-winded response to your claim, but it's pretty much just to assure you that you're thinking along the correct path. People prey on other's eagerness to be accepted into a community. Whether that's risque under-age cam shots, talking them into incredibly dumb shit then posting it, or just general fuckery.
If you want to know the name of asshole numero-uno, just look up: Violentacrez
