There's been no official word yet from TCU confirming or denying the arrest last night, but that arrest has now been substantiated through several other means, including the release of the mug shot itself. ESPN has a story up with a few short blurbs, but the best account is still available through NBCDFW's website.
Ralph Drusso from the Associated Press tweeted that Pachall has been suspended indefinitely in the wake of the news, but that has yet to be confirmed (as far as I know) by TCU.
I'll update this thread with any new information as it becomes available. If I had to guess, though, we've seen the last of Pachall in a TCU uniform for a while, if not for the entire rest of the season. Patterson set too strong a precedent in the summer to back down now simply because he needs this player. In Pachall's absence, TCU will likely turn to redshirt freshman Trevone Boykin to play QB.
For more TCU news, check out their SB Nation blog. They'll be talking about this quite a bit, I imagine.