How can she explain all this clean-up? Washing the knife to make sure no trace evidence would remain. Throwing the gun and rope into the desert. At some point, she lost her GPS (??) and got rid of her clothing.
If she TRULY shot him/killed him in self-defense and would have reported it immediately, wouldn't that have given her a better chance if they presented this defense?
Maybe I'm stupid, that's just how I think.