Investigators say guides used a range of methods to force helicopter evacuations, including faking medical emergencies and lacing food with large amounts of baking powder to stimulate gastric distress commonly associated with altitude sickness. Others were given medications with excessive amounts of water to trigger symptoms.

After trekkers reported nausea, dizziness or body aches, they were advised to descend and agree to costly emergency helicopter evacuations. Authorities said operators then used forged medical and flight documents to claim costs from international travel insurers.