The co-pilot of Germanwings 9525 had sole control of the doomed flight that crashed into the French Alps early Tuesday and appeared to want to "destroy this plane," a French prosecutor told The Associated Press.
The cockpit voice recorder, recovered on Wednesday from the rugged terrain north of Nice appeared to show the pilot clocked out of the cockpit and knocking on the door, first politely, then frantically in the moments before the jet, carrying 150 passengers and crew, began a rapid descent that killed all aboard.
Brice Robin, a Marseilles-based prosecutor told Reuters the evidence from the cockpit voice recorder, one of two "black boxes" and the only one recovered so far, seems to show the co-pilot, identified as Andreas Lubitz, refusing to open the cabin door as he began the eight-minute descent "manually and intentionally."
Screams can be heard from passengers in the final seconds of their lives, officials said. The Airbus 320, which was en route from Barcelona to Dusseldorf, crashed into the mountain at 435 miles per hour, officials said.
Germanwings, a low-budget carrier operated by Lufthansa, did not release the name of the pilot. Robin insisted in a news conference Thursday morning that Lubitz, a German from the central city of Montabaur, was not a known terrorist.
"A terrorist?" he said in response to a question. "Absolutely not."
Still, it was the co-pilot's "intention to destroy this plane," Robin said. The recorder captured his normal breathing patterns, suggesting Lubitz was not incapacitated.
The airline said the captain had more than 6,000 hours of flying time and been Germanwings pilot since May 2014, having previously flown for Lufthansa and Condor, a German leisure airline. Lubitz, 28, joined Germanwings in September 2013, directly after training, and had flown 630 hours. Lufthansa chief executive Carsten Spohr described both pilots as "experienced and trained."
The plane was about halfway through its flight when it descended from a cruising altitude of 38,000 feet to around 6,000 feet in approximately eight minutes. During that time, whoever was in the cockpit did not respond to radio calls from French air traffic controllers, who alerted authorities when the plane disappeared from their radar screens.
Overnight, AFP reported that one of the cockpit seats was pushed back and the access door opened and closed. Moments later, a source told the agency that knocking could be heard, but there was no conversation between the pilots. The source added that an alarm warning of the plane's proximity to the ground could be heard just before impact.
The New York Times report cited a senior military official involved in the investigation who said the knocking grew increasingly frantic as the Airbus 320 plummeted to earth.
"The guy outside is knocking lightly on the door, and there is no answer," the investigator said. "And then he hits the door stronger, and no answer. There is never an answer ... You can hear he is trying to smash the door down."
The Wall Street Journal, citing Airbus training materials, reported that many Airbus jets are fitted with crew-controlled locks designed to prevent unauthorized access to the flight deck. In some planes, the cockpit can be accessed through a keypad code, but pilots can also lock out external access for five minutes or longer by flipping a certain switch in the cockpit.
The Daily Telegraph, citing the German newspaper Bild, reported that air traffic controllers had tried three times to contact the plane after a final communication from the captain was received at 10:30 a.m. local time. Seconds later, the plane began descending.
Bild's report, which cited a purported leaked copy of a timeline compiled by the controllers, said that attempts were made to contact the plane at 10:31, 10:35, and 10:36, with the last two attempts made on the international distress frequency. At 10:40 a.m., the plane vanished from the radar.
Remi Jouty, the director of France's aviation accident investigation office, told reporters Wednesday that investigators had been able to extract sounds and voice from the damaged voice recorder, but cautioned "at this stage, we don’t have the slightest explanation or interpretation as to what led this plane to fly down."
Officials have not formally ruled out any possible cause of the crash, though France's Interior Minister said early Wednesday that he did not believe terrorism was the likely cause "at the moment." At his press conference Wednesday, Jouty told reporters that the small pieces of debris from the plane indicated that the jet was intact when it hit the ground and did not explode in midair.
The Associated Press contributed to this report.