The co-pilot who appeared to want to deliberately destroy the Alps crash Germanwings plane was called Andreas Lubitz, French authorities said.
The prosecutor said Lubitz was 28 years old. He joined Germanwings in September 2013, directly after training, and had flown 630 hours.
Marseille prosecutor Brice Robin said the co-pilot was alone at the controls and "intentionally" sent the plane into a doomed descent, after refusing to open the door to the captain.
During a visit to the crash site, the boss of Lufthansa has avoided reporters' questions about the co-pilot's known depression.
Newly-released footage shows Germanwings co-pilot Andreas Lubitz in flight around ten years ago during his time as a trainee.
Pilots with a history of depression should not be banned from flying, a leading British psychiatrist has said.