From what I've gathered from the posts & input from everyone in this group, this, to me, is the most likely timeline.
Aug 27 - BL kills GP in a fit of rage. (Not planned.)
Aug 28-29 - BL hikes alone to the Northwest (or hitchhikes)
Aug 29 - BL hitchhikes back to GP (Confirmed by 2 drivers), begins driving home?
Aug 30 - BL begins/continues home. Likely also calls home.
Sept 1 - 11am - BL arrives home. Just to buy himself time to think, talks about a breakup. NOT a crime.
Sept 11 - Gabby’s parents’ freak out; Brian has to talk to his parents to ensure they don’t respond
Sept 11-13 - Brian ends up sharing everything with his parents
Sept 13, PM - Brian leaves home on a “camping trip.”
Sept 13-15 - Brian kills himself.
Sept 14-16 - Parents don’t share Brian is gone because it looks suspicious. They haven’t decided what to do yet so want to buy time & protect him in the meantime
Sept 17 - Parents decide it’s been too long, are worried about Brian. SB suggests his odd parsing of them offering to help with Brian, but NOT with Gabby, as “they are two separate investigations”
Sept 17-Oct 21 - Parents prod LE to keep searching in the place where they eventually find Brian.
Obviously MOO!