On March 24, Germanwings flight 9525 crashed into the French Alps, resulting in the deaths of all 150 people on board. It was recently discovered that the plane’s co-pilot purposely caused the crash.

The 27 year old Andreas Lubitz, was said to have waited until the pilot left the cockpit to deliberately declin the elevation of the plane. The transponder data showed that someone reprogrammed the autopilot to go from 38,000 feet to 100 feet.

The plane’s cockpit recorder captured the last few moments of the Germanwings passengers. Screams were heard, as well as the pilot’s banging on the cockpit door, which had been locked by Lubitz.

There are still no clues to why Lubitz had the intention of crashing the plane.

Lubitz was with Lufthansa since September 2013 and completed around 630 hours of flight time. He passed all medical qualifications and certifications.

Lufthansa has no standardized psychological test that determines mental state, but the company does take mental state into consideration when hiring.

Pilots must have a first class medical certificate, which is to be renewed every year if the pilot is under 40 years old and every six months if the pilot is 40 or older. Pilots must also visit an FAA-approved medical examiner and fill out a form that requires the pilot to disclose any existing medical conditions and medications.

In light of these precautions, it is difficult to determine how Lubitz could have had a mental illness that was not discovered.

Friends and relatives of the victims were flown in by Lufthansa to an area near the site of the crash. They were given special accommodations to stay at a hotel in the village of Seyne-les-Alpes. Lufthansa has also given financial support to the relatives of the victims.

Investigators believe that Flight 9525 was destroyed by Lubitz possibly do to a mental illness. Therefore, the case becomes a question of whether Lubitz was at fault for not revealing his illness in the past, or Lufthansa is at fault for not putting in place any specific psychological tests.

Investigators continue to search for more clues in the plane’s second flight data recorder.