"Initial reports I've read are that the boy he says was fatally shot by police was first non-fatally shot in the bicep, and then fatally shot in the chest."

Yes, also Mark Duggan was 29 - hardly "a boy".

Edit: Actually, while it's been confirmed that Mark Duggan was shot in the bicep and (fatally) in the chest, I don't think they've established the order in which the shots were fired.