Germanwings co-pilot appeared to want to 'destroy the plane': French prosecutor

France: The co-pilot "deliberately" initiated the descent of the Germanwings flight that crashed into the French Alps and refused to open the door to the pilot who was outside the cockpit, the lead investigator said on Thursday.

The co-pilot, named as 28-year-old Andreas Lubitz, appeared to "show a desire to want to destroy" the plane, prosecutor Brice Robin told reporters.

"The co-pilot was alone at the controls," said Robin, presenting information gathered from the "black box" recorder that records sounds and conversations from the cockpit.

"He ... refused to open the door of the cockpit to the pilot and deliberately began the descent of the plane."

Lubitz was identified as a German citizen who was not known to have any links to terrorism or extremists, Robin said, adding that German authorities were expected to provide additional information on his background and private life later Thursday or Friday.

Read: Germanwings crash: Co-pilot had 630 hours flying experience, says Lufthansa

The co-pilot turned the "flight monitoring system" button to initiate the plane's descent and spoke "not a single word" during the last 10 minutes before the plane crashed.

The passengers were unaware of their imminent demise "until very last moment" and "died instantly", the prosecutor said.

He said screams could be heard on the recording only in the final seconds.

Read: Lufthansa says Alps crash ‘inexplicable’, Germanwings plane was ‘in perfect condition’

The recording showed that the pilot and co-pilot talked normally and "courteously" for the first 20 minutes of the flight after it took off from Barcelona.

"Then we hear the pilot ask the co-pilot to take the controls and a seat being pulled back and a door closing. We can assume he left to answer nature's call," said Robin.

"The co-pilot is left alone at the controls. We hear several calls from the pilot asking for entry into the cockpit. There is no response from the co-pilot."

Robin said there were "normal" breathing sounds from Lubitz throughout the rest of the flight that indicated he was conscious.

Read: Germanwings to cancel more flights as crew members refuse to fly

"The co-pilot is alone at the controls," said prosecutor Brice Robin, recounting information gathered from the "black box" recorder. "He voluntarily refused to open the door of the cockpit to the pilot and voluntarily began the descent of the plane."