As news unfolded of investigators determining that Tuesday’s crash of Germanwings Flight 9525 in the French Alps was an intentional act by the plane’s co-pilot, the world went into shock. What could have motivated co-pilot Andreas Lubitz, 28, to intentionally kill 150 people, including himself?

Once the jet’s voice recorder was analyzed, it became clear to authorities that Lubitz had locked the cabin door while the pilot was in the lavatory. The recorder later registered pounding on the door by the captain in an attempt to re-enter the cockpit. At the same time, investigators said the co-pilot took the plane off autopilot and pushed a manual button to begin a landing-style descent into the mountains. It was a disciplined descent, much like pilots make at an airport. After analyzing the audio, investigators said passengers appeared to be tragically unaware of anything abnormal until seconds before the crash.

After investigators released their stunning findings, the big question pivoted from the what to the why?

Although it has been reported that there was a gap of several months in Lubitz’s training, there have been no hints thus far of radical lifestyle changes or connections to terrorism. Most seem to agree that Lubitz was, by all initial accounts, a seemingly normal young man with a love of flying and sports.

Reporters and others immediately descended on Lubitz’s hometown – Montabaur, Germany, not far from Frankfurt – to determine who this man was. Reuters reported that he was a seemingly typical twenty-something German. He had loved flying since age 13 and had belonged to sailplane and glider sports clubs. The head of his local flight club described him as “a perfectly normal guy.” Others in the club described him as “integrated,” social and not a loner.

The BBC listed other crashes suspected to be caused by “deliberate pilot action,” including the LAM Mozambique Airlines crash in 2013, the EgyptAir crash in 1999 and the SilkAir crash in 1997.

Questions are also resurfacing about the unresolved Malaysia Airlines Flight MH370 crash last year in the Pacific. Could that tragedy have also been due to deliberate pilot action? The answer may never be known.

One question, however, may have been answered by French prosecutor Brice Robin, as reported by The Guardian. If investigators are correct that Andreas Lubitz crashed Germanwings Flight 9525 on purpose, that wouldn’t just make him a man who committed suicide. It would make him a cold-blooded murderer of innocent men, women and children.

“When you commit suicide, you die alone,” Robin said. “With 150 on the plane, I wouldn’t call that suicide.”