Who dropped the dime on the Apple e-book five?

How did the Department of Justice’s e-book case get started? How did it go so wrong? And, most intriguingly, who fed the DOJ's investigators all the details? In other words, who dropped the dime? We may have to wait for the trial to get definitive answers, but there are enough thinly veiled hints in the complaint to allow some educated guesses.

• The "corporate superior" who provided e-mails translated from French would have to be Hachette, the only co-defendant based in France.
• The "large print and e-book retailer" whose e-mails from Penguin CEO David Shanks are quoted verbatim could only be Barnes & Noble (BKS), an Amazon competitor whose share of the e-book market grew to 27% after Apple introduced the so-called "agency model" and whose share price dropped 6.4% one day after the antitrust suit was filed.
• And the unnamed "non-defendant publisher CEO" who makes at least five appearances in the complaint is, according to three sources who declined to go on the record for fear of angering the largest and most powerful publisher in New York, Markus Dohle, CEO of Random House.