flight was headed when it left the radar screen. so far, they're just discussing what we already know. here's what is driving this bizarre turn. a senior malaysian air force official tells cnn the jet liner veers hundreds of miles off course. top malaysian officials however now disputing that claim, but they're also saying that they're expanding the search into that area. this as we're learning that the plane's transponder was turned off. why did that happen? so we've got the latest on the search and the investigation into its disappearance beginning with jim clancey. >> reporter: hot day here in kuala lumpur. especially hot for the defense