The co-pilot of the Germanwings flight 4U9525, Andreas Lubitz, deliberately crashed the airplane into the Alpine mountainside, said the prosecutor.

In light of the new revelation, police have raided the house of the co-pilot to look for clues.

The account of the final moments of Germanwings Flight 9525 suggested that the German co-pilot purposely crashed the Airbus carrying 150 passengers.

Marseille Prosecutor Brice Robin said, "We have no idea of the reason." The conclusions came after the investigators reconstructed the final moments of the flight from the jet's black box voice recorder. They said co-pilot Andreas Lubitz's intention was "to destroy this plane."

German, French, and U.S. officials held that there was no indication of terrorism.

However, the prosecutor did not give explanation on why investigators do not suspect a political reason; instead the investigators are focusing on the German co-pilot's "personal, family and professional environment" in an attempt to ascertain why he did it.

According to Robin, Lubitz, who sounded courteous in the first part of the journey, became "curt" when the captain started the mid-flight briefing on the planned landing of the jet.

As per the information retrieved from the black box, the pilot, who has not been identified, left the cockpit for a seeming bathroom break, and Lubitz took control of the airplane. He, all of a sudden began a manual descent, and the pilot started knocking on the door. However there was no response.

The prosecutor said, "It was absolute silence in the cockpit," --except for the stable breathing, which suggested Lubitz was not panicked, and did the act in calm, deliberate way.

The sad incident has prompted some airlines to instantly impose sterner cockpit rules.