The co-pilot at the controls when Germanwings Flight 9525 crashed in the French Alps earlier had an “existing illness” and should not have been working for medical reasons, authorities say.

Andreas Lubitz, 27, has been identified as the co-pilot who investigators say “intentionally” steered a Germanwings airliner into a mountainside earlier this week, killing all 150 passengers on board.

Ralf Herrenbrueck, a spokesperson for the Marseille prosecutor, said in a statement Friday, that Lubitz concealed a doctor’s note excusing him from work on the day of the crash. The torn-up note was found at one of Lubitz's residences in Germany.

Medical records indicate Lubitz had “an existing illness” and went through “appropriate medical treatment,” Herrenbrueck said.

He added that no suicide note was found and Lubitz left no indications that his actions were politically or religiously motivated.

Neighbours near Lubitz’s family home in Montabaur described him as a happy, quiet, physically healthy man.

One Montabaur acquaintance said he showed no signs of depression when he renewed his glider pilot’s license last fall.

“He was happy he had the job with Germanwings and he was doing well,” glider club member Peter Ruecker said. “He gave off a good feeling.”

Ruecker said Lubitz earned his glider pilot’s license as a teenager after finishing his education at a tough German college preparatory school. Lubitz was then accepted as a pilot trainee at Lufthansa.

Ruecker described Lubitz as a “rather quiet,” but friendly man.

Lubitz’s glider club, LSC Westerwald, acknowledged his death in a statement on their website Wednesday, before authorities implicated Lubitz in the crash.

“With great dismay, the members of the LSC Westerwald eV have heard of the crash of Germanwings flight 4U9525,” a translation of the statement said. “With horror, we acknowledge that among the dead is a long-time member of our association.”

On Thursday, LSC Westerwald chairman Klause Radke rejected the notion that Lubitz intentionally crashed the plane.

“I don’t see how anyone can draw such conclusions before the investigation is completed,” Radke told AP.

“He really took care of himself,” said Johannes Rossmann, who lives a few doors down from Lubitz’s family home in Montabaur. “He was very healthy,” she told AP.

German news media are portraying Lubitz as a depressed man who struggled to get over a bad break-up with his girlfriend.

Authorities have not confirmed that Lubitz suffered from a form of mental illness.

On Thursday, Marseille prosecutor Brice Robin said Lubitz locked the aircraft’s pilot out of the cockpit and intentionally set the Germanwings plane on its fatal course with the intention to “destroy the plane.”

Robin told reporters that Lubitz initially sounded calm talking to the aircraft’s captain in flight recordings obtained from the crash. However, his responses became more “curt” when the captain began discussing plans for landing.

The captain then left the cockpit to use the bathroom, at which point Lubitz locked the cockpit door, Robin said. The captain returned and knocked on the door, then tried to break it down when Lubitz refused to answer.

Anti-hijacking locks prevented the captain from breaking into the cockpit, Robin said.

Robin said Lubitz remained completely silent as he accelerated the aircraft’s descent, up until it slammed into the mountain.

Robin refused to offer details on Lubitz’s religion. “I don’t think it’s necessarily what we should be looking for.”

German Interior Minister Thomas de Maizire said Lubitz showed “no indications of any kind of terrorist background.”

Lufthansa, the parent company of Germanwings, said Lubitz had 630 hours of flying experience. He joined the company in September of 2013 after completing his flight school training in Bremen, Germany and Phoenix, Arizona.

Germanwings CEO Thomas Winkelmann said Lubitz showed no red flags when he started his pilot training in 2008. However, his training was interrupted for a period of time before he was cleared to continue.

“He was fit for flying without any restrictions,” Winkelmann said at a joint news conference with Lufthansa executives on Thursday.

Lufthansa CEO Carsten Spohr said he was “stunned” by the conclusion that Lubitz crashed the plane.

“We choose our staff very, very carefully,” he said.

Spohr and Winkelmann could not explain why Lubitz took a break for “several months” during his training six years ago.

Spohr added that all pilots undergo a yearly medical examination. However, that examination does not include psychological testing.

A Facebook page belonging to an Andreas Lubitz was set to inactive within days of the crash. The page showed he participated in several road races and had an interest in aviation.

It also included several photos of travel destinations around the world, and images taken from the windows of an airplane.