The confusion I have about this crime is why she waited until she did to kill him versus sneak into his house and use the gun (and only the gun) and be out of there much faster. She arrives in the middle of the night and it's more than 12 hours later when she kills him.
In the meantime she's already established a timeline and an expectation that she will be in SLC with the new guy, and he's waiting for her.
There's just so much plain stupidity to go with the evil. I guess it's possible she didn't decide to absolutely kill him until later, but she was otherwise prepared with a gun, had changed her hair color, had a rental car, set up a visit to SLC, etc. Instead she spreads her DNA around, hair, pictures, just the most ludicrous stupid things and when she finally does decide to kill him, instead of one or 2 shots in the shower, she's all about the knife and leaving puddles of blood, which only serve to point right at her.
Such a dumb girl. And evil. Dumb and evil.