BERLIN: The Germanwings co-pilot investigators believe purposely crashed a plane last week by locking out his captain from the flight deck had researched suicide methods and cockpit-door mechanics prior to the incident, prosecutors said.

Data retrieved from a tablet computer at the Dusseldorf home of Andreas Lubitz showed that he looked up the information in the days prior to the March 24 crash that killed all 150 people on the Airbus A320, the Dusseldorf prosecutors said on Thursday.

Lubitz, 27, who had a sick notice for the day of the crash that he concealed from his employer, also looked for medical assistance on the device, the prosecutor said.

The latest findings support the suspicion that Lubitz willfully brought down the aircraft after denying his captain re-entry into the cockpit from a short toilet break while the plane was at cruising altitude. Since the crash, a picture has emerged of a young pilot who had battled depression and interrupted his flight training at Deutsche Lufthansa, only to be readmitted after medical experts found him fit to proceed.

Salvage crews on site in the French Alps have managed to retrieve the flight-data recorder, the second so-called black box on the aircraft that helps investigators reconstruct a plane’s performance prior to an incident. The teams had already found the voice recorder, which had taped conversations and sounds in the cockpit and provided the first clues that Lubitz had consciously brought the single-aisle jet down.

The two data recorders are being investigated in Paris at the BEA aircraft accident bureau, which is leading the probe. There’s “reasonable hope” investigators will be able to analyze the content from the second black box, Marseille Prosecutor Brice Robin said at a press conference Thursday.