Before he took control of a plane full of passengers and crashed it into the French Alps last month, Germanwings pilot Andreas Lubitz might have spiked his captain's coffee with a diuretic drug to make him leave the cockpit and go to the bathroom, the Mirror reported Wednesday. Lubitz, 27, researched diuretic drugs, which increase the need to urinate, online before he reportedly locked flight captain Patrick Sondenheimer out of the cockpit and crashed the plane on March 24, killing all 150 people on board.

Prosecutors have been scouring Lubitz's online records for clues as to why he took the plane down. He also researched "cockpit doors" and "suicide" days before crashing the plane, German prosecutors revealed last week.

Sondenheimer had two children and was only on the flight because he wanted to go home to spend more time with his family. The cockpit voice recorder suggests Sondenheimer desperately tried to enter the cockpit after he was locked out, at one point smashing the door with a crow bar. "For God's sake, open the door," he yelled.

Lubitz was in therapy for suicidal tendencies before becoming a pilot. More recently, he consulted at least five doctors, including psychiatric specialists and a neurologist, Der Spiegel reported

Lufthansa, the parent company of Germanwings, said Lubitz passed all medical and “fit to fly" tests. French aviation officials have said they would investigate whether “systemic weaknesses” of the airline contributed to the Germanwings crash, including psychological profiling.

"He voluntarily refused to open the door of the cockpit to the pilot and voluntarily began the descent of the plane," said Brice Robin, a prosecutor in Marseille investigating the crash, last month.

Lubitz reportedly used the username “Skydevil” to log on to his computer. He had recently completed Internet searches on "bipolarity," "manic depression," "migraines," "impaired vision” and "acoustic trauma."