This "kid" may or may not be found guilty of murder, but you'd have to admit, he is monumentally screwed. There's no going back after the knowledge of killing two people and wounding a third. To me, the failings of his parents, schools, friends and society has allowed this happen.
He'll need severe psychiatric help the rest of his life. He shouldn't ever be trusted to make his own decisions ever again and be placed under Conservatorship. Since he is only 18, he should be confined to an institution at least for five years, to allow his brain to process his actions and rehabilitate his thought patterns.
Sad, no matter how the verdict goes.