PARIS, March 26 -- There is no indication that the Germanwings plane crash was an act of terrorism, said Brice Robin, prosecutor of the Republic, in a press conference held Thursday in Marseille, broadcast by BFMTV.

The co-pilot, identified as Andreas Lubitz, 28, of German nationality, is "not listed as a terrorist," said Robin, but insisting "nothing indicates in favor of a terrorist attack".

During the press conference, Robin, prosecutor of the Republic in Marseille, who just met with some families of the victims of the Germanwings' Airbus 320 that crashed Tuesday in the French Alps, revealed more details of what happened in the cockpit before the crash.

"We have the transcript of the last 30 minutes of flight," announced the prosecutor.

"During the first 20 minutes, we could hear friendly and even playful (verbal) exchanges" between the pilot and co-pilot, he explained, adding no words was spoken in the last 10 minutes.

After analyzing the audio file from the black box retrieved Tuesday afternoon, Robin said the captain left the cockpit with the aircraft on autopilot. Once alone, the co-pilot deliberately manipulated the controls to gradually lower the altitude of the aircraft from 12,000 meters to 2,000 meters.

Confirming the co-pilot deliberately locked the cockpit door, the prosecutor said the captain tried many times, without success, to enter the cockpit, and "the action of the first officer of the crashed Germanwings' A320 can be analyzed as his intention to destroy the aircraft."

Also according to the file extracted from the black box, no words was spoken in the last 10 minutes of Germanwings' crashed A320 in the cockpit, but the sound of "normal breathing" of the co-pilot was recorded till the moment of the crash.

"No message of emergency was received by the air traffic controllers" from the Germanwings' A320 plane, confirmed Robin, adding that the passengers should have no idea of what was happening until the crash occurred.

The aircraft A320 operated by Lufthansa's Germanwings crashed Tuesday in the southern French Alps while flying from Spain's Barcelona to Germany's Duesseldorf with a total of 150 people on board.