Another passenger saw the man doing something suspicious and watched him.

When the plane landed, the passenger told the backpack's owner what he saw.

A photo shows people waiting at Changi Airport in Singapore.

The owner checked his bag and found that 250 euros were missing.

Police found the suspect using information from the passenger and video footage.

The police arrested the suspect and got the money back.

The man could go to jail for up to three years or pay a fine under Singapore law.