Co-pilot appeared healthy, but had hidden illness.

Byline: Geir Moulson and David McHugh

MONTABAUR, Germany -- Germanwings co-pilot Andreas Lubitz appeared happy and healthy to acquaintances, but a picture emerged Friday of a man who hid evidence of an illness from his employers -- including a torn-up doctor's note that would have kept him off work the day authorities say he crashed Flight 9525 into an Alpine mountainside.

As German prosecutors sought to piece together the puzzle of why Lubitz locked his captain out of the cockpit and crashed the Airbus A320, police in the French Alps toiled to retrieve the shattered remains of the 150 people killed in Tuesday's crash.

Searches conducted at Lubitz's homes in Duesseldorf and in the town of Montabaur turned up documents pointing to ''an existing illness and appropriate medical treatment,'' but no suicide note was found, said Ralf Herrenbrueck, a spokesman for the Duesseldorf prosecutors' office.

They included ripped-up sick notes covering the day of the crash, which ''support the current preliminary assessment that the deceased hid his illness from his employer and colleagues,'' Herrenbrueck said in a statement.

Doctors commonly issue employees in Germany such notes excusing them from work, even for minor illnesses, and workers hand them to their employers. Doctors are obliged to abide by medical secrecy unless their patient explicitly tells them he or she plans to commit an act of violence.

Prosecutors didn't specify what illness Lubitz may have been suffering from, or say whether it was mental or physical. German media reported Friday that the 27-year-old had suffered from depression.

The Duesseldorf University Hospital said Friday that Lubitz had been a patient there over the past two months and last went in for a ''diagnostic evaluation'' on March 10. It declined to provide details, citing medical confidentiality, but denied reports it had treated Lubitz for depression.

Neighbors described a man whose physical health was superb and road race records show Lubitz took part in several long-distance runs.

''He definitely did not smoke. He really took care of himself. He always went jogging. ... He was very healthy,'' said Johannes Rossmann, who lives a few doors from Lubitz's home in Montabaur.

People in Montabaur who knew Lubitz told The Associated Press that he had been thrilled with his job at Germanwings and seemed very happy.

On Friday, no one was seen coming or going from his family's large slate-roofed two-story house in Montabaur as...