Malaysia Airlines Flight 370: Former deputy CIA Director Mike Morell says plane likely flew south

Malaysia Airlines Flight 370 likely did not fly over a northern route suspected by some investigators, according to former Deputy Director of the CIA Mike Morell, because it would likely have been detected by the numerous countries the plane would have been forced to traverse.

"A lot of defense radar up there with China and India and the U.S. and Afghanistan," he said on "CBS This Morning." "...It's most likely the southern route."

Morell said the most interesting thing about this investigation is that "it really seems that somebody took control of this aircraft and flew it for some time after the communications systems were turned off."

The investigation has now turned to the flight's pilot and co-pilot.

The Wall Street Journal has released a report saying "some senior U.S. officials believe that the plane may have been taken as part of a 'dry run' for a future terrorist attack, testing the ability to take a plane and hide it from radar and satellites."

Though Morell said it's a possibility, he said it's unlikely someone would do something of this magnitude as a test.

"If you were able to get control of an aircraft, you would use it immediately," Morell said.

As for a report that the plane may have dropped below 5,000 feet to avoid radar, Morell said he talked with Boeing 777 pilots, and they claim that the difficult technique known as "terrain masking" is possible, but not likely.

Turning to the Malaysian officials and how the search has been conducted, "CBS This Morning" co-host Charlie Rose asked if Morell is surprised by what they haven't done.

"No," Morell replied. "In general, they are very, very cooperative. They are very cooperative with us on counterterrorism. They are very good, but there is a natural tendency in these situations to want to let everybody know you can do an investigation yourself. So a natural tendency to be a little reluctant to accept help."

Morell continued, "In addition, this is a very interesting neighborhood with a lot of disputed islands so the last thing you want to do is hand over defense information to your adversaries. So I'm not surprised at this point."

As for al Qaeda in the region, Morell said Malaysia was one of the places where the group used to spend some time, but "Malaysians have largely...pushed al Qaeda out."

For more with Morell, watch his full "CTM" interview above.