The second black box from the site of last week’s Germanwings plane crash has been found, French police say, as German authorities reveal that co-pilot Andreas Lubitz had searched on a computer for ways to commit suicide shortly before the crash.

The Germanwings flight crashed in the French Alps at a speed of 700 kilometres per hour, killing all 150 people on board.

Investigators have previously said that the plane’s cockpit voice recorder indicated co-pilot Andreas Lubitz locked the captain out of the cockpit and deliberately crashed the plane.

The second black box, the flight data recorder, contains readings from hundreds of parameters of the Airbus A320 jetliner including any pilot commands.

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The Marseille prosecutor in charge of the case, Brice Robin, said French investigators believed there was a “reasonable hope” that the second black box could provide useful evidence despite suffering some damage.

It is expected to be thoroughly analysed by France’s Bureau d’Enquetes et d’Analyses (BEA) crash investigation authority, which will try to match the data with cockpit voice recordings and information from ground radar.

After a nine-day hunt, the second data recorder was found by a French gendarme in a ravine, buried 20 centimetres down in a place that had been searched several times already, Mr Robin said.

It had caught fire and was blackened and damaged.

Germanwings co-pilot Andreas Lubitz. Photo: AAP

Germanwings parent Lufthansa said it welcomed the discovery of the second box and hoped it would produce results.

Mr Robin also said 150 sets of DNA had been found in the wreckage, corresponding to the number of passengers and crew on board.

He stressed, though, that the discovery of 150 DNA sets did not mean all the victims had been found.

At each matching of a DNA set to a victims, families would immediately be informed, he said in a news briefing in Marseille.

In addition, 470 personal items have been found which include 42 mobile phones, but Mr Robin said they looked unlikely to yield anything useful.

“These telephones are in a very, very damaged condition, which will certainly make extracting information from them very, very difficult,” he said.

On the same day French police confirmed the discovery of the second black box, German state prosecutors said they believed Lubitz had searched on a computer for ways to commit suicide shortly before the crash.

In a statement, prosecutors in Dusseldorf said the computer, which they had found in his home, also showed searches on cockpit doors and safety precautions related to them.

They said Lubitz had “looked for information on ways to commit suicide” in computer searches that took place between March 16 and 23, one day before the crash.

“On at least one day, the person had for several minutes undertaken searches related to cockpit doors and their safety precautions,” it added.

Lufthansa has come under pressure to explain what it knew about the co-pilot’s history of depression and could face substantial claims for damages, according to legal experts.

The German newspaper Bild reported on Thursday that Lubitz had allegedly lied to doctors, telling them he was on sick leave rather than flying commercial planes.