German media claims Andreas Lubitz spiked captain's coffee before deadly crash

Andreas Lubitz deliberately crashed a passenger plane into a mountain killing all on board. Photo / Supplied

Andreas Lubitz, the co-pilot who deliberately crashed a Germanwings passenger flight into the Alps, may have spiked the captain's coffee in order to get him out of the cockpit, it has been claimed.

A German newspaper suggested the Lubitz may have mixed a diuretic drug into Capt Patrick Sondheimer's drink, which would have made him need to go the lavatory.

The claim comes amid reports that Lubitz searched online for information about diuretic drugs in the run-up to the crash.

But it appears to be largely based on speculation, with no evidence that Lubitz actually bought the drugs or took them with him in the flight.

Investigators believe Lubitz deliberately locked Capt Sondheimer out of the cockpit so he would be alone at the controls to crash the aircraft.

The captain, had briefly left the flight deck in order to visit the lavatory.

The captain complained he hadn't had time to visit the lavatory before take-off, and Lubitz more than once offered to take control so Capt Sondheimer could slip out.

The leaked transcript has not been verified.

German prosecutors have confirmed that they found evidence Lubitz searched online for information about suicide and cockpit doors in the weeks leading up to the crash.

But they have declined to comment on the diuretic claims.