New details emerge about Germanwings co-pilot who deliberately crashed a plane

The deliberate crash of Germanwings Flight 9525 on the morning of March 24, 2015 stunned the world.

Now, a little less than a year later, GQ's Joshua Hammer has written an investigative article into the pilot behind the crash that killed 144 passengers and six crew members.

The pilot, Andreas Lubitz - who had received psychiatric treatment for depression and allegedly hid the extent of his illness from his employer - wrote a note called "Decision Sunday," with the flight code for Barcelona - where the doomed flight had originated - on March 22, two days before the crash.

The note, retrieved by investigators from a trash can in the Dusseldorf apartment shared by Lubitz and his girlfriend, listed three options: "[find the] inner will to work and continue to live," "[deal with] stress and sleeplessness," and "let myself go," Hammer reports.

The Telegraph initially reported on the existence of the note on September 21, 2015, but didn't include the direct quotes.

The crash was the culmination of a tough period in Lubitz's life. In early March 2015, Lubitz's search history indicated that he was considering suicide, and on March 20, he searched for details about the locking mechanism on an Airbus 320 cockpit door, according to Hammer.

On March 18, Lubitz was placed on four days of sick-leave by a physician, who wrote a note saying that Lubitz suffered from "a persistent vision disorder with a thus far unknown origin," which could have been psychosomatic, according to The New York Times.