The co-pilot of Germanwings 9525 had sole control of the doomed flight that crashed into the French Alps early Tuesday and "wanted to destroy this plane," a French prosecutor said Thursday.

The cockpit voice recorder, recovered on Wednesday from the rugged terrain north of Nice, appeared to show the pilot locked 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.

In a Paris news conference, Marseille prosecutor Brice Robin said 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 8-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 early into the mountain at 435 mph, officials said. Three American passengers also perished.

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.

"It wasn't the breath of somebody who was struggling,” the prosecutor said. “He didn't say a single word. Total silence."

Asked when passengers realized their fate, Robin said, "We only hear screams at the very end. Death was instant.”

Robin said the commander of the plane knocked several times "without response." He said the door could only be blocked manually.

He said the co-pilot's responses, initially courteous, became "curt" when the captain began the mid-flight briefing on the planned landing.

The information was pulled from the black box cockpit voice recorder, but Robin said the co-pilot did not say a word after the commanding pilot left the cockpit.

"It was absolute silence in the cockpit," he said.

During the final minutes of the flight's descent, pounding could be heard on the cockpit door as plane alarms sounded, but the co-pilot's breathing was normal throughout the whole time, Robin said.

"It's obvious this co-pilot took advantage of the commander's absence. Could he have known he would leave? It is too early to say," he said.

In the German town of Montabaur, acquaintances told The Associated Press that Lubitz showed no signs of depression when they saw him last fall as he renewed his glider pilot's license.

"He was happy he had the job with Germanwings and he was doing well," said a member of the glider club, Peter Ruecker, who watched Lubitz learn to fly. "He gave off a good feeling."

Lubitz had obtained his glider pilot's license as a teenager, and was accepted as a Lufthansa pilot trainee after finishing a tough German college preparatory school, Ruecker said. He described Lubitz as a "rather quiet" but friendly young man.

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, the co-pilot did not respond to radio calls from French air traffic controllers, who alerted authorities when the plane disappeared from their radar screens.