Wallace tells Veronica that he can't believe Josh killed his dad and ran off like that. Have you noticed how useless Wallace's character has gotten? Kid, my advice is to watch your back. Veronica's chagrined to see Logan and Parker eating together. These two just should avoid the cafeteria altogether.
Mindy returns to the interrogation room for a surprise: Keith is now the sheriff. People wondered about this, but I don't see why the Commissioner wouldn't be able to appoint his choice of interim sheriff until the next election. Keith shows her pictures of the bloody clothes (the shirt being monogrammed "HBL"), and tells her that they belong to Landry: "So either you're covering for him or he's covering for you, and you're gonna tell me which it is right now." So she's either going to pick "I killed him" or "I didn't kill him." I wish they wouldn't end the show on stumpers like that.
So who did it? I'm guessing Lucky Tim. We know he's privately contemptuous of Landry, and it certainly seems like someone is trying to frame him. Tim would be able to do an excellent job of that, even down to the clothes -- as one astute poster pointed out on the boards, Lucky Tim at least used to handle Landry's dry cleaning. I don't know what his motive would have been in killing the Dean, though. If he did it, was he bitter about the decision to bring back the fraternities, given his freak-out at that party? Or was the Dean simply the only plausible victim to use to frame Landry? Who knows? We'll find out soon enough. In the meantime, Michael Muhney? Best of luck in things to come.