Report: Germanwings co-pilot was being treated for depression

Andreas Lubitz, the Germanwings co-pilot prosecutors believe intentionally crashed flight 9525 into the French Alps, was being treated for depression, the Wall Street Journal reports.

A person familiar with the investigation told the Journal that Lubitz was not only being treated for depression, but also hid news of his treatment from his employer - Lufthansa's low cost subsidiary Germanwings.

Investigators believe Lubitz locked the flight's captain out of the cockpit as the 28-year old junior co-pilot flew the Airbus A320 airliner into a mountainside.

According to the Wall Street Journal source, there is no evidence that would indicate Mr. Lubitz was on any "mind-altering medication" at the time of the incident.

Earlier on Friday, prosecutors say that a doctor's note stating that the pilot was unfit to fly on the day of the crash was found at Lubitz's residence Dusseldorf, Germany.

Lubitz reportedly ripped up medical leave notes that had been issued to him and according to Germanwings were not submitted to the airline.