You should be kept as far away from the justice system as possible.

You just "othered" me. You just called for me to be undemocratically removed from the political process, entirely because you don't agree with my opinions. I have not been tried or convicted in any crime, or otherwise been the subject of any sort of due process that would strip me of any rights or privileges.

Your position is therefore undemocratic.

I do, indeed, understand that children slowly bear more and more responsibility for their own actions as their cognition and experience increases. What you don't seem to understand is that the cognitive abilities and experiences necessary to comprehend the rightness and wrongness of murder are typically developed well before age 10. You further fail to understand that this kid possessed them. He knew what he was doing. This wasn't some youthful indiscretion, or a simple failure to control his impulses. This was a deliberate act. He specifically went looking to kill someone, and succeeded.

You asked me several comments up to consider my own behavior at age 15. I never murdered anyone, and I knew that murdering people was wrong before 15. Long before 15. The overwhelming majority of kids are sufficiently responsible to use deadly weapons for hunting and sport before reaching their teens.

Murder stops being tolerable as soon as the individual is capable of deliberately causing it. This kid was capable of such deliberation. He is irredeemable.