I don’t know much about this case really. But something makes me think this young man may have been set up and was trying to do a ‘Fugitive’ run. He must have known some shit- or disrupted a plan? Ill bet that notebook says “Hey everyone, I’m sorry for killing her, please forgive me” and just like that - case closed
https://www.dailywire.com/news/fbi-calls-petito-death-murder-following-recovery-of-laundrie-notebook-backpack?