DENVER, July 10 /PRNewswire-FirstCall/ -- Qwest Communications International Inc. (NYSE: Q) said it was informed by the U. S. Attorney's office in Denver yesterday afternoon that it had begun a criminal investigation of Qwest. The U.S. Attorney's office did not disclose the subject matter of the investigation. Qwest plans to fully cooperate with the U.S. Attorney's office. (snip)