The conspiracy theorists are owed an apology. You can read all about it at: Everything Is Rigged: The Biggest Price-Fixing Scandal Ever. Money (heh) quote:

But the biggest shock came out of a federal courtroom at the end of March – though if you follow these matters closely, it may not have been so shocking at all – when a landmark class-action civil lawsuit against the banks for Libor-related offenses was dismissed. In that case, a federal judge accepted the banker-defendants’ incredible argument: If cities and towns and other investors lost money because of Libor manipulation, that was their own fault for ever thinking the banks were competing in the first place.