Lufthansa announced Tuesday that Andreas Lubitz—the co-pilot of the Germanwings flight that crashed into the French Alps last week, killing all 150 people on board—had previously informed the airline of a "serious depressive episode."

According to German newspaper Die Welt, authorities found clear signs of a "serious psychosomatic illness" when searching the home of Germanwings co-pilot Andreas Lubitz.

Citing unnamed officials with knowledge of the investigation, The New York Times reports that the man believed to have intentionally crashed a Germanwings plane earlier this week sought medical treatment for vision problems.

Police in Germany reportedly discovered documents indicating that Andreas Lubitz—the co-pilot of the Germanwings plane believed to have been intentionally crashed, killing 150 people—may have been hiding a medical condition from his employers. Investigators also claim to have found a torn up doctor's note excusing him from work.