SPOILERS I wish they'd revealed the killer to be...
...Richie.
And by that I mean Richie being the guy who blew up Patton. That would have been a huge reveal and a great explanation for how Patton got taken out. And it'd be a huge table flip in the struggle between Rusty and Richie's little war.
They can still reveal it in Season 2, but man, it would have been so nice to find that out in the season finale.