Chandra, 45, a supervisor at the Tambaram railway reservation counter, was robbed of an eight-sovereign gold chain in the first class coach of an EMU while returning from work on Thursday night, police said.
The thief, aged around 25 years, boarded the compartment as the train started moving at Trisulam station.
He snatched Chandra’s gold chain and jumped out from the train before it picked up speed. There were just a couple of other passengers in the first class coach and they could not react in time, police said.