Procter & Gamble’s multibillion dollar deal to sell its Pringles snack food business to Diamond Foods is on the ropes, now that prosecutors have opened an investigation into payments that Diamond made to walnut growers. The probe could result in criminal charges, according to an article in The Wall Street Journal. The SEC has already been looking into the payments, and will coordinate with the U.S. Attorney’s office in San Francisco. The company is also conducting an internal in...