• Police searched Germanwings Flight 9525 co-pilot Andreas Lubitz`s apartment in Dusseldorf, Germany, on Thursday, the city`s police spokesman said in televised comments. A team of five investigators went "through the apartment looking for clues as to what the co-pilot`s motivation might have been, if he did indeed bring the plane down," police spokesman Markus Niesczery said.

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The co-pilot of Germanwings Flight 9525 purposely crashed the plane into the French Alps, killing all 150 people on board, officials said Thursday.

"We at Lufthansa are speechless that this aircraft has been deliberately crashed by the co-pilot," said Carsten Spohr, CEO of Lufthansa, which owns Germanwings.

Marseille prosecutor Brice Robin said the co-pilot, 27-year-old German national Andreas Lubitz, apparently "wanted to destroy the aircraft."

It`s unknown whether Lubitz planned his actions, Robin said. But he "took advantage" of a moment in which the pilot left the cockpit and "activated the descent," which can only be done deliberately.

New details released Thursday appeared to support the startling revelation that someone set the plane on a crash course.

Transponder data shows that the autopilot was reprogrammed during the flight by someone inside the cockpit to change the plane`s altitude from 38,000 feet to 100 feet, according to Flightradar24, a website that tracks aviation data.

The plane`s cockpit audio recorder captured horrific sounds. The captain, somehow locked out of the cockpit, can be heard banging on the door, Robin said.

And screaming can be heard on the audio recording for the final few minutes of the flight.

For those on board when the plane plunged into the mountains, Robin said, death was instantaneous.

No clues about why co-pilot would crash plane

Police searched Lubitz`s apartment in Dusseldorf on Thursday, looking for clues about his possible motive.

A search is underway for the plane`s second "black box," the flight data recorder, which could shed more light on the plane`s final minutes.

And the French government has asked the FBI to help investigate the crash, a law enforcement official said.

Investigators so far say they`re baffled about why Lubitz would have crashed the plane

Lufthansa does "not have any clues," Spohr said.

The picture of the plane`s final minutes comes largely from what was discovered in the mangled cockpit voice recorder.

The pilot and co-pilot had normal exchanges during the beginning of the flight, Robin said. When the pilot stepped out to go to the bathroom, he asked Lubitz to take over.

It`s unclear whether the pilot entered a code to try to get back into the cockpit when he returned, or whether Lubitz "put the lever on lock," which would have prevented the code from working, Spohr said.

The most plausible explanation of what happened next is that Lubitz, "through deliberate abstention, refused to open the cabin door ... to the chief pilot, and used the button" to cause the plane to lose altitude, Robin said.

The disaster is not being described as a "terrorist attack," and the killing of 150 people would generally not be described as a "suicide" either, Robin said. Spohr agreed: "If a person kills himself and also 149 other people, another word should be used -- not suicide," he said.

Lubitz was not known to be on any terrorism list, and his religion was not immediately known, Robin said.

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