initial tests on the flight data recorder recovered from downed germanwings show that co-pilot andreas lubitz purposely used the controls to speed up the plane 's descent .
the pilot modified the autopilot setting to increase the speed of the -lrb- airplane -rrb- in descent .
investigators have focused on lubitz 's health as they try to establish his motivation .
but the search history was not deleted and also revealed searches concerning medical treatment .