Bumping for Dave.
New account but longtime member, my other username is too identifiable...
Though I haven't seen Dave in many years, we had spent some time together. Our groups are estranged.
Just some insights in case they help, though it looks like family and friends are on board.
He's described as slim, but he is tough as nails slim. He is literally the last person you want to get in a fight with, both because of his strength and the fact that he won't quit. He is also very intelligent, though you wouldn't know it until something trivia came up and he knows the answers.
I can't speak to his mental state because it's been so long. He would be familiar with the detox facility procedure though and that's a possibility, but it's been over a month now.
It's telling that his car hasn't been found. Accident? Runner? I hope the family get answers soon.