I don't know much about criminal law, but I think you're right about aggravated murder being the only capital felony. However, it seems to me that if he killed her to perpetuate or cover up his lies, or to avoid supporting a child that is "pecuniary or other personal gain."
Also, you'll be interested to know that criminal homicide includes the killing "an unborn child at any stage of its development." So, if they can confirm the pregnancy, he'll be facing two counts.
Maverik is open very late -- maybe all night long. I'm not sure. They're all over the place. I have no idea where the one is that he stopped at. The local news is reporting that the clerk told police that Mark came in all the time to buy cigarettes, and he told the clerk not to let his wife know that when they stopped in Sunday evening to buy sodas.
Mormons don't smoke. He might have lied about that at some time to participate in some of the things that require complete observance. Not a big thing compared to murder, of course, but says something about basic character.
I can look out my office window and see the entrance to Memory Grove, and the Hacking apartment is about five blocks from here. I'm sure it took less than five minutes to get from the apartment to Memory Grove. Bountiful takes about 15 minutes, with probably another 5 or 10 minutes to get up into the hills above Bountiful.
One interesting new thing I learned today. I talked to my daughter in Portland for the first time since all this happened. She is the closest in age to Mark and Lori.
I've said before that one of my daughters knows Mark's sister Sarah, and another knows his sister, Julie. Both of them were, according to my girls, the nicest people imaginable, and complete straight arrow. My daughter in Portland was one year younger than Lori, and two years younger than Mark. She used to go out socially in a group that included Mark's younger brother, Chad. Again, Chad was an incredibly nice young man.
But she said that Mark used to hang out with boys that had a little bit of a reputation for misbehavior, and seemed quite impressed with himself. She had the sense that Mark was different than the rest of his family. It's very possible that he wasn't living up to the requirements to go on a mission, and lied about it in order to go. Again, just speculation. But this is the first time I have heard anything other than that Mark was just like the rest of his siblings.
Utah Code Ann. §§ 76-5-201, et seq. declares that a person commits criminal homicide if he intentionally, knowingly, recklessly, causes the death of another human being, including an unborn child.
Utah considers any stage of pregnancy to be a viable fetus under the law - so this would be a double homicide.
If news accounts I've read so far are accurate, he may not have known she was pregnant, since it was reported that Lori had told her sister-in-law (who said she saw the positive pg test) that she was planning to tell Hacking some days hence as a sort of timed surprise. But who needs the "pecuniary gain" element (in this case, a "pre-emptive" gain) when you've already got (1)(b)?
Amazingly small world re your daughters' acquaintance with the Hacking kids. I believe Sarah is the sister Lori confided in about her pregnancy. I suspect Althany will be calling small armies of character witnesses if this makes it to trial. The prosecutor could counter by sending out "invitations" to people like your daughter (oops!).
Reading your description of your daughter's impressions re Mark and putting them together with everything else I've learned about him and his family, I'm put in mind of what Dr. Robert Hare has said about sociopaths -- that they're born, not made. Doing a little speculating of my own, my guess is that while Mark's parents were undoubtedly shocked and horrified by the murder, they both knew deep down that Mark had always been a mischief maker and liar.
One point you may be able to help me with is the whole issue of temporary insanity and how it could apply in a case like this in Utah. When the police were quoted by Fox News as calling this a "rage killing," I was thinking in California mode (always risky) and cringed since, in this state, a phrase like that could only help the defendant. Do the exclusions to affirmative defense cited at bottom of post 164 do away with the McNaughton rule?