Re: "The Dark Knight Rises" Review and Discussion Thread (spoilers)
They couldn't have pinned Dent's death on the Joker as he'd already been arrested before Harvey took his fall. Even the GCPD aren't that dumb as to accept a guy in a cell miles away could have done it.
And they don't want to admit that Joker had turned dent to the darkside so that leaves Batman to take the the fall.
Gentlemen you can't fight in here - this is the war room.
Pres. Merkin P. Muffly