Investigators are attempting to uncover more information about the co-pilot who appears to have deliberately crashed the ill-fated Germanwings passenger jet.
A French prosecutor turned the spotlight on 28-year-old Andreas Lubitz who was at the controls of the plane that was carrying 150 passengers and crew.
Details of the last 10 minutes of the A320 flight came from audio files from the cockpit voice recorder.
The prosecutor, Brice Robin, says Lubitz was left alone at the controls when the captain went to the toilet, shortly after hitting cruising altitude over the French Alps.
The co-pilot refused to unlock the cockpit door when the captain returned and the plane was deliberately put into a steady descent.
The prosecutor says it appears Lubitz wanted to “destroy” the aircraft. He was known to be breathing normally right up until the impact.
The sound of the captain attempting to smash the door down, as well as screaming from passengers, are reportedly heard on the cockpit flight recorder.
Robin says the passengers would not have been aware of what was going on until just before the impact.
However, it seems likely that many will have witnessed the captain’s desperate attempts to break down the door and his pleas for the co-pilot to let him in.
Robin says the change to a gradual descent would have to be intentional and there was no reason for the co-pilot not to open the door or respond to air traffic controllers.
Lubitz joined the airline directly after a training course. He had just 630 hours of flying experience and joined Germanwings in 2013.
By comparison, the pilot of the ill-fated flight had more than 6,000 hours of flying time and had been with the airline for more than 10 years.
In response to the tragedy, numerous airlines have now announced changes to their rules, saying there must always be two cabin crew in the cockpit during flights.
The jet crashed while en route from Barcelona to Dusseldorf with 144 passengers and six crew. It came down in rugged mountainous terrain about 10 kilometres from the village of Seynes-les-Alpes. A search and recovery operation has been set up there.
The recovery of victims’ remains and debris from the aircraft is expected to be long and difficult.
The area is difficult to access and the impact of the crash means the plane has been shattered into small pieces.
French prosecutor Robin said Lubitz was not known as a terrorist and there was nothing to suggest the incident was a terrorist act.
The German interior minister has also said there is no evidence that Lubitz had any links to terrorism.
On Wednesday the leaders of France, Germany and Spain visited the scene of the tragedy.
Most of the passengers were German and Spanish.