Andreas Lubitz, Germanwings co-pilot: The tortuous trail to 'Why?'

Also learning more about those final moments on flight 9525. Investigators sifting through the wreckage looking for more clues. ABC's David Kerley is here with those details. Good morning, David. Reporter: It is about that all-important question now, why?

Germanwings co-pilot Andreas Lubitz, suspected of deliberately bringing down the plane with 150 people on board, suffered depression and underwent psychiatric treatment, German media report.

Germanwings flight 4U9525 co-pilot Andreas Lubitz took a long, unexplained break in his training six years ago, according to Lufthansa CEO Carsten Spohr. Lubitz, who started training in 2008, was deemed "100% fit to fly" and passed psychological and 

Also learning more about those final moments on flight 9525. Investigators sifting through the wreckage looking for more clues. ABC's David Kerley is here with those details. Good morning, David. Reporter: It is about that all-important question now, why?

Andreas Lubitz, 28, intentionally started the descent of flight 4U9525 while the pilot was locked out of the cockpit, French prosecutors said yesterday. Reports this morning suggested the pilot may have been badly affected by a