If the killers are caught, they won't be executed--and they will probably be free to walk the streets at 21 and hunt for some more victims.
I don’t think anyone who would shoot a baby could think it through that far. This was either a nitwit “Sarah Smith” stun or the act of feral nitwit.
Still, one thinks of the Einsatzgruppen who were filmed shooting mothers shielding babies with their bodies and then shooting the babies. I’d like to think that I would have shot myself first.