The co-pilot of the crashed Germanwings plane, Andreas Lubitz, had received treatment for suicidal tendencies years ago, investigators have said, but not in recent doctor visits.
Lubitz is suspected of deliberately crashing the plane in the Alps, killing all 150 people on board.
Officials in Duesseldorf said that the investigation had so far shown no clue to any motive.
So far, DNA strands of 80 of the victims have been found.