The captain called out several times to be let back into the cockpit.
The plane that crashed into the Alps killing 150 people was deliberately brought down by the deranged co-pilot.
Twenty-eight-year-old co-pilot Andreas Gunter Lubitz, pictured here at the Golden Gate Bridge in San Francisco, locked the captain out of the cockpit, then flew the plane straight into a mountainside.
French prosecutor Brice Robin said, "We hear the captain calling out several times asking to be let into the cockpit. He does this by videophone, but there is no reply from the co-pilot."
The bone-chilling details of the final minutes of the doomed flight were revealed by a French prosecutor today.
"There can be heard the sound of human breathing from the cockpit and this can be heard until the final impact, meaning the co-pilot is alive all this time," said Robin.
Disturbingly, the passengers can also be heard screaming as they realized the plane was about to crash.
The captain was locked out using a mechanism designed to lock cockpit doors from the inside following the 9/11 terrorist attacks.
On U.S flights the door can be opened from outside using a keypad and a secret code in an emergency.
Aviation expert Robert Goyer told INSIDE EDITION, "If people commit suicide, it's a tragic thing. But to take out 150 people along with you, I don't think we'll ever be able to wrap our heads around why it is that someone would choose to do that."
Among those killed were three Americans, including 23-year-old Emily Selke of Virginia and her mother, Yvonne.
Two prominent opera singers, Maria Radner and Oleg Bryjak were also among the victims. They were flying home from a performance in Barcelona.
The co-pilot who crashed the plane had been working for the airline for only 18 months. He was trained in Phoenizx, Arizona, but there was also an unexplained break in his training of several months apparently due to a "medical issue."
The shocking development is an echo of the crash of an EgyptAir flight from New York to Cairo off Nantucket. The co-pilot was found to have deliberately crashed the plane into the ocean.
And there is speculation that a similar scenario of pilot suicide may have caused the crash of that missing Malaysia flight last year. The pilot, who had his own flight simulator at his home, has come under increasing scrutiny.
And an American pilot of a Jetblue airplane had to be locked out of the cockpit and restrained by passengers after he went crazy during a flight in 2012.
Now, another shocking pilot suicide, taking 150 other lives with him.
