Do we have any information about Steven's movements in October and November, or even earlier? Did he have episodes of driving long distances at other times?
We know he drove from St George to Bountiful and back, twice in November. Once was for a wedding/birthday party (his own, a couple of weeks late?) and Thanksgiving -- and that he evidently returned to St George the day after Thanksgiving, because he helped PD put up Christmas lights.
On Thanksgiving, he was in WVC, Bountiful and then back in WVC before driving home the next day. He seemed like "a driver" -- but we have no other details. Those events were timelined by the family, so I'd suspect if he made other trips home OR to see others he knew, they'd have mentioned it in their early search to trace his movements.
IF he was driving elsewhere, apparently there's no trace.
Since he didn't hide his driving on Dec 10th and 12th, wouldn't it be logical that there'd be previous traces on the bank accounts and litter in the car?
Also, after rereading the LL's posts about the rent, and the other information, it's not clear to me whether Steven was behind on his *own* rent, or whether what he hadn't paid was JZ's unpaid share. That happened to my brother once, when he discovered that since he and his roommate didn't have separate contracts with the landlord, he was obligated for all the rent after the roommate skipped town ahead of his ex-wife's alimony collectors. If it was something that he got stuck with due to the roomie's misbehavior, and then his father scolded him about bad money management, Steven's anger would be understandable.
Did your brother know the roommate previously, and did they move in together and sign the contract together?
From what the LL's wife said, I understood that Z and SK each rented a bedroom in the home separately, with joint sharing of the living room, kitchen and bathroom. There's no indication they knew each other, and we don't even know which one of them moved in first.
I believe what Steven owed, was his own share. It was only around $1,000+ after three months (with, apparently, the fourth month due on Dec 1st). That's about $350 plus utilities; certainly, they wouldn't have rented the whole home (minus one bed and bath) to two people for that amount.