The co-pilot suspected of deliberately crashing a Germanwings airliner into the French Alps hid details of an illness, Germanprosecutors say.
Torn-up sick notes were found in the homes of Andreas Lubitz, they say, including one for the day of the crash, which killed 150 passengers and crew.
A German hospital confirmed he had been a patient recently but denied reports he had been treated for depression.
Lufthansa, which owns Germanwings, has announced new flight safety rules.
The new regulations are meant to ensure pilots are never left alone in the cockpit. Data from the voice recorder suggests Mr Lubitz purposely started an eight-minute descent into the mountains while keeping the pilot locked out of the flight deck.
There were no survivors when Flight 4U 9525 crashed in a remote mountain valley on Tuesday while en route from Barcelona in Spain to Duesseldorf in Germany.
Prosecutors say there was no evidence of a political or religious motive for his actions and no suicide note has been found.