passengers on board from 14 different countries played no role? >> to say that everybody's been cleared is really an outrageous statement in my mind. this takes many months to do a thorough investigation. to me that's a stretch and i would not have confidence in that statement. >> the focus of the investigation is now more squarely on the crew members, especially the pilots. down to every minute detail, what they ate, whether they ate the same meals, and even who prepared the food. >> just looking for anything out of the ordinary, anything unusual. somebody that might snow something, something that might have been potentially put into the food. >> but sources telling cnn investigators believe the culprit was in the cob pit. overnight we learned malaysia airlines sent out a security memo noting no pilot or first officer is allowed to be left alone in the cockpit. adding to the mystery and perhaps confusion, officials say today they haven't ruled out mechanical failure as a possible cause even though they're