The black box voice recorder indicates that Andreas Lubitz, 27, locked his captain out of the cockpit on Tuesday and deliberately sent Flight 4U 9525 crashing into a mountainside, French officials say, in what appears to have been a case of suicide and mass murder.
French Prime Minister Manuel Valls said that "everything is pointing towards an act that we can't describe: criminal, crazy, suicidal."
German prosecutors revealed today that searches of Lubitz's homes netted "medical documents that suggest an existing illness and appropriate medical treatment", including "torn-up and current sick leave notes, among them one covering the day of the crash".
But Bild daily earlier reported that Lubitz sought psychiatric help for "a bout of serious depression" in 2009 and was still getting assistance from doctors, quoting documents from Germany's air transport regulator.
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The paper also cited security sources as saying that Lubitz and his girlfriend were having a "serious crisis in their relationship" that left him distraught.
Lufthansa CEO Carsten Spohr said that Lubitz had suspended his pilot training, which began in 2008, "for a certain period", before restarting and qualifying for the Airbus A320 in 2013.
According to Bild, those setbacks were linked to "depression and anxiety attacks".
Duesseldorf prosecutors said the evidence found in the two homes "backs up the suspicion" that Lubitz "hid his illness from his employer and his colleagues".
They said they had not found a suicide note, confession or anything pointing to a "political or religious" motive but added it would take "several days" to evaluate the rest of what was collected.
Lubitz locked himself into the cockpit when the captain went out to use the toilet, then refused his colleague's increasingly desperate attempts to get him to reopen the door, French prosecutor Brice Robin said.