“I did a thorough checking of my bag,” said Mokhtar, “because my biggest concerns were my traveling documents (passport etc.) and whether he had implanted any illegal items in an attempt to use me as his transporter (read: drug-mule syndicate).” The cabin crew was alerted to the situation and immediately called security and the police, which removed the man from the flight and filled in a report with Mokhtar.
Mokhtar was later informed by the cabin crew that “there is a syndicate that has been conducting this modus operandi on China, Hong Kong, and Vietnam flights.” According to an article in The Economist, Hong Kong police have reported a 25% increase in cabin-baggage robberies in 2015, up to 60 incidents total.
The Economist reports a dramatic incident when a Turkish businessman had $260,000 in cash and goods stolen from his overhead luggage in 2016 while he was traveling to Hong Kong.
Following the incident, Mokhtar warned flyers to “please be careful of your belongings, and use extra safety tools, i.e. bag locks, and do travel in groups when possible.” 
H/T: AirlineRatings