That's because according to investigators, everything is on the table. in fact, officials now believe the plane might have been sending out electronic signals or pings four to five hours after its radar beacons stops transmitting. tonight we've just learned that u.s. officials believe the radar beacon or transponder was shut down separately from the system that continued sending out the empty pings 14 minutes apart. that could be extremely significant. american investigators telling abc news that the two modes of communication were quote systematically shut down, which makes for a very big hou...