M Ashwini, who was studying B.Com, died on the spot as the assailant stabbed her with a knife after confronting and picking up an argument with her, they said.
The man, identified as Alagesan, was nabbed by bystanders and thrashed before being handed him over to police.
The motive for the murder, which sent shockwaves, was under investigation, police said.
Quoting eyewitnesses, police said Alagesan confronted the victim near her college and picked up an argument. Then all of a sudden, he took out a knife and stabbed her and attempted to flee.
Three men had been arrested in connection with the incident.
In 2016, a 26-year old techie Swathi was murdered on the platform of a suburban railway station here around 6 AM while waiting to board a train. A man arrested on the charge of killing her later allegedly committed suicide in the prison.
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