Germanwings crash co-pilot Andreas Lubitz researched suicide methods on his tablet computer just days before his passenger jet struck the French Alps, prosecutors said Thursday.
Analysis of search terms from the browser history on a device seized during a raid on his home suggested the co-pilot of doomed Flight 4U9525 sought information about medical treatments as well as "types and implementation methods of a suicide," Attorney-General Ralf Herrenbrück from the Dusseldorf prosecutor's office said in a statement.
"On at least one day, the concerned person spent several minutes with search words about cockpit doors and their security measures," he added.
Prosecutors believe Lubitz locked his captain out of the Airbus A320's cockpit and intentionally crashed the plane — en route from Barcelona to Duesseldorf — into a mountainside on March 24. All 150 people aboard were killed.
Analysis of the evidence found at Lubitz's house is preliminary and was expected to take many more days to verify, Herrenbrück stressed. The browser history covered the period from March 16 - 23.
The crash has thrown a spotlight on the opaque world of mental health screening for pilots, who face regular physical testing but are often expected to self-declare illnesses such as addiction or depression.
Earlier Thursday, German ministers announced a review of airline safety procedures including cockpit door mechanisms and medical testing for pilots.
This article originally appeared on NBCNews.com.