The pilot who flew a packed Germanwings aircraft into the French Alps was suffering from vision problems and showed signs of "psychosis", investigators have confirmed.
They said - "without a shadow of a doubt" - that 27-year-old Andreas Lubitz had deliberately destroyed the plane on 24 March.
All 150 people on board were killed and the plane reduced to thousands of pieces during the devastating 460mph crash.
In a Paris new conference, prosecutor Brice Robin said Lubitz suffered from severe depression and had seven medical appointments, including three meetings with a psychiatrist, in the month before the tragedy.
Mr Robin said Lubitz had written to his doctor to tell him he was sleeping just two hours a night and had doubled his dosage of anti-depressants.
He also mentioned his fear of going blind.
Over five years, Lubitz had seen 41 doctors.
Some of them believed he was suffering "psychosis" and was not fit to fly but medical privacy rules meant his employers could not be informed.
Doctors in Germany can be jailed if they break the rules - unless there is evidence the patient is going to commit a serious crime or harm themselves.
Lubitz saw things 30% darker than normal and also experienced bright flashes, reporters were told.
Doctors could not establish whether or not his condition was psychosomatic.
Germanwings' parent company, Lufthansa, says Lubitz had passed all required medical tests and had been cleared to fly.
The 27-year-old locked the pilot out of the cockpit during the flight and had practised his suicidal descent, as well as researching suicide methods.
Air traffic control tried 11 times on three frequencies to contact Lubitz as he lost altitude and aimed the plane at the mountainside.
Investigators also met families on Thursday who are desperate to find out when they will get access to their loved ones' remains and possessions.
The meeting with Marseille prosecutor Brice Robin is also thought to have broached the delicate issue of compensation.
German lawyer Peter Kortas, representing relatives of 24 of the victims, said negotiations with Germanwings over compensation had started a few days ago.
"In this moment everything else is not as important as the fact that the bodies, (the) remains be returned to their families," he 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," said the lawyer.
"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."
Relatives have been frustrated by delays.
The severity of the impact has made it difficult for workers to find and identify remains - most of the bodies were reduced to fragments and needed DNA to be identified.
There have also been mistakes made on death certificates.
However, some victims have finally been released to their families.
Hearses carrying 15 of 16 classmates from one German high school yesterday returned them to their home town of Haltern.
The remains of 44 people, including the 15 children, arrived in Dusseldorf - the city where the doomed flight was supposed to land nearly three months ago.
The victims on the flight - which took off from Barcelona - were from 19 different countries.
Nearly half of the victims were German and 47 were Spanish.
Three judges are now taking over the case, which has formally been upgraded to a "manslaughter" investigation, and will determine if anyone can be held liable for the tragedy.