I don't know the facts of the case; the article was too scant. This seems closer to manslaughter than a deliberate murder. For me, I question whether the death penalty is necessary or even life in prison. I'm not saying what she did wasn't heinous; and I'll reiterate that my opinion is very much from the outside looking in.
This is Arizona. I've lived there. It's like living in a frying pan. Even if that slope faced skank was a full blown retard, she'd still know that inside a car truck in Arizona is going to be like an OVEN, that's why she put the kid in there, she knew damn well it was going to be HOT. She murdered that kid same as if she blew his head off with a shot gun.
She should be locked in a car trunk same as the kid until she's dead, then dump her baked carcass out in the desert and let the scorpions and tarantulas eat it.