Not necessarily referring to only your post - just jumping off here.
I am not sure what to believe with kids anymore. There is so much violence in this world I find it almost impossible for a 10 year old to NOT know what COULD kill someone. I mean, if he wanted to "hurt her" a kick to the shin is sufficient. Holding a 90 year old FRAGILE woman down by the throat with her cane, punching her in the stomach until blood comes out her mouth seems to me a little more than just wanting to just hurt her.
It certainly didn't seem to cause any sort of panic or remorse from what I'm reading...unless the story just isn't telling the whole story of how he'd suddenly realized what he'd done and screamed or ran to get someone to help.
JMO of course...I'm hoping more details come out because right now I'm finding about ZERO sympathy for this kid. We have to open our eyes to the reality of how dangerous kids can be, when they have, on more than one occasion, proven they can be. Did he set out that day to kill her? No...probably not. Doesn't mean he's not a danger now, and forever.