Germanwings Flight 9525 co-pilot Andreas Lubitz researched suicide methods and cockpit doors days before crashing the plane last week in the French Alps and killing all 150 people on board, officials revealed.
Investigators discovered the information after finding an iPad belonging to Lubitz at his apartment in Düsseldorf, and went through the browser history from March 16 to March 23, The New York Times reported.
"During this time, the user was searching for medical treatments, as well as informing himself about ways and possibilities of killing himself," prosecutors said in a statement.
"On at least one day, the person concerned also spent several minutes looking up search terms about cockpit doors and their safety measures."
Torn-up doctor's notes have also been found in Lubitz' apartment, revealing he was unfit to fly on the day of the crash. Medical reports have further noted that Lubitz was treated for a "severe depressive episode" that interrupted his flight training six years ago, but he then showed improvement and earned his license.
Investigators have said that Lubitz deliberately crashed the Airbus A320 jet last week in the French Alps, after locking the cockpit door and keeping the captain out.
The leaked audio transcript revealed that Lubitz had locked the cockpit after Capt. Patrick Sondenheimer had stepped out to go to the bathroom, and refused to open it despite the captain's pleas and attempts to break in.
CNN reported that the second black box has now also been found, containing additional flight data that could provide more clues as to what happened.
The recorder was found eight inches below the surface by a female police officer digging through a ravine, prosecutor Brice Robin said.
"We will be able to identify the speed, the altitude and the way the pilot acted ... which will be critical," Robin predicted.
As to whether the newly discovered evidence proves that the murder-suicide was planned in advance, German criminal psychologist Gaby Dubbert said that premeditation is common in such cases.
"Based on the cases in my study, the majority of murder-suicides are planned, planned well ahead of time," Dubbert said.
Robin further noted that searchers have found over 470 personnel effects at the crash site, including 40 badly damaged cell phones.
Investigators have rejected claims that cell phone footage of the flight's final moments was found, though two publications, German daily Bild and French Paris Match, claimed that they have seen the video and described it in detail.
"One can hear cries of 'My God' in several languages," Paris Match reported. "Metallic banging can also be heard more than three times, perhaps of the pilot trying to open the cockpit door with a heavy object.
Toward the end, after a heavy shake, stronger than the others, the screaming intensifies. Then nothing."
Investigators have also isolated 150 different sets of DNA from the crash site, though Robin said that more work needs to be done to identify the victims.
"It doesn't mean we have identified 150 victims. We need to compare (the recovered DNA to) DNA from the families and the deceased," he noted.