JOIN USRajinder Singh, 33, who hails from India's Punjab state, was electrocuted Sep 29 when he fell on the metro rails. Some accounts say he was pushed by the 22-year-old suspect.
Rajinder Singh stopped the suspect from harassing a young woman in the train in which all three were travelling.
They got off at Crimée station. During a row, Singh was electrocuted, RFI radio web site reported.
The French media is describing Rajinder Singh as a hero.
The woman has not come forward to testify, RFI said. Police said they do not know if the suspect pushed the man.
The suspect was arrested from a bar in the Pigalle red light district after detectives recognised him from CCTV footage.
Rajinder Singh came to France seven years ago and found work delivering pizzas. According to media reports, he sent money home to his family every month.