Germanwings co-pilot who crashed flight feared going blind

Robin said the investigation so far "has enabled us to confirm without a shadow of a doubt ... Mr. Andreas Lubitz deliberately destroyed the plane and deliberately killed 150 people, including himself."

Investigators say Lubitz locked the pilot out of the cockpit and flew the plane into a French mountainside, after having researched suicide methods and cockpit door rules and practiced an unusual descent.

Robin said Lubitz had also investigated vision problems, and "feared going blind" a career-ending malady for a pilot. Lubitz had suffered depression in the past and been on anti-depressants.

Lubitz had seven medical appointments within the month before the March 24 crash, including three appointments with a psychiatrist, Robin said. Some of the doctors felt Lubitz was psychologically unstable, and some felt he was unfit to fly, but "unfortunately that information was not reported because of medical secrecy requirements," the prosecutor said.

Doctors risk prison

In Germany, doctors risk prison if they disclose information about their patients to anyone unless there is evidence they intend to commit a serious crime or harm themselves.

German prosecutors have said he had no actual physical ailments. Robin said Lubitz complained of seeing flashing lights but that there was no apparent "organic" reason for Lubitz's apparent vision troubles.

Germanwings and parent company Lufthansa have said that Lubitz had passed all medical tests and was cleared by doctors as fit to fly.

The question for investigators now is who could be held responsible. The prosecutor upgraded the investigation from a preliminary probe to a full-fledged manslaughter inquiry, which hands the case to investigating magistrates who can file eventual charges against people or entities.

German lawyer Peter Kortas, whose firm represents relatives of 34 victims, said negotiations with Germanwings about compensation began several days ago. Families were also seeking answers about delays in the return of victims' remains.

"In this moment everything else is not as important as the fact that the bodies, (the) remains be returned to their families," Kortas said. "It's already more than two and a half months since the crash happened, so it's finally necessary to get to closure."

"The loss of the relatives should be compensated with also a suitable amount of money," he added. "There are two points in these negotiations: First, the material loss for the material damages, and it is also about damages for pain and suffering."

Nearly half of the victims were German, 47 were Spanish and there were 17 nationalities among the remainder.