The sounds recorded on one of the "black boxes" recovered from downed Germanwings Flight 9525 firms up investigators' theory that the co-pilot locked the captain out of the cockpit and then crashed the plane.

"For God's sake, open the door!" Capt. Patrick Sondenheimer screamed as he banged on the cockpit door, pleading with the co-pilot.

Thirteen minutes later, the plane slammed into the French Alps.

The audio from the plane's cockpit voice recorder has not been released, but the German newspaper Bild published what it claims is a summary of the transcript from the recording.

CNN translated Bild's report -- which the newspaper says is based on the 1.5 hours of audio that was on the cockpit voice recorder -- but cannot independently verify the information.

Before takeoff, Sondenheimer tells co-pilot Andreas Lubitz that he didn't manage to go to the bathroom in Barcelona, Spain, according to Bild. Lubitz tells him he can go any time.

Lubitz is believed to have locked the pilot of Flight 9525 out of the cockpit before putting the plane on a rapid descent into the mountains, French authorities have said.

The flight took off 20 minutes late. After reaching cruising altitude, Sondenheimer asked Lubitz to prepare the landing.

Once that's finished, Lubitz tells the captain he "can go anytime."

There is the sound of a seat being pushed backward after which the captain says, "You can take over."

At 10:29 a.m., air traffic radar detects that the plane is starting to descend.

Three minutes later, air traffic controllers try to contact the plane and receive no answer -- shortly after which an alarm goes off in the cockpit, warning of the "sink rate," Bild reported.

Next comes the banging.

Sondenheimer begs Lubitz to let him in. Passengers then begin to scream, according to the transcript obtained by Bild.

Another three minutes pass. A loud metallic bang is heard at 7,000 meters (almost 23,000 feet).

A minute and half later and 2,000 meters (about 6,500 feet) lower to the ground, an alarm says "Terrain -- pull up!"

"Open the damn door!" the pilot says.

It's 10:38, and the plane is at 4,000 meters (about 13,000 feet). Lubitz's breathing can still be heard on the voice recorder, according to Bild's report.

Two minutes later, investigators think they hear the plane's right wing scrape a mountaintop.

Screams can be heard one final time.

'Unbelievable' leak

CNN's Richard Quest called it "unbelievable" that the black box audio would be leaked in this manner.

Cockpit recordings are some of the most sensitive and closely held parts of aviation crash investigations. They're never officially released, according to Quest.

Communications between air traffic control and a plane's cockpit can be downloaded privately, but that's less common in Europe than it is in the United States.

An edited and redacted version of the transcript is usually published in part of a final report on an incident.

Anxiety, burnout and depression

Lubitz suffered from "generalized anxiety disorder," and from severe depression in the past, Le Parisien newspaper reported Sunday, citing sources close to the investigation. In 2010, Lubitz received injections of antipsychotic medication, the paper reported.

He was also prescribed a medication that influences neurotransmitters, but it's unclear when that happened, Le Parisien said.

Investigators found a handful of pills in his apartment in addition to two sick notes, which forbade him from working from March 16 to March 29, according to the paper.

News reports also stated that antidepressants were found in Lubitz's apartment this week.

Die Welt, a German newspaper, cited an unidentified senior investigator who said that Lubitz suffered from a severe "psychosomatic illness" and that German police seized prescription drugs that treat the condition. Lubitz suffered from a "severe subjective burnout syndrome" and from severe depression, the source told Die Welt.

The New York Times also reported that antidepressants were found during the search of his apartment. CNN has not been able to confirm the reports.

French authorities have said that Lubitz appeared to have crashed Germanwings Flight 9525 deliberately into the Alps on Tuesday as it flew from Barcelona toward Dusseldorf, Germany, with 150 people on board.