An aide of arrested Trinamul councillor Anindya Chatterjee was arrested on Sunday based on a Salt Lake resident's complaint that the leader's gang had demanded Rs 12 lakh from him to let him renovate his house.
Dipankar Sen, 38, a resident of Baguiati who had allegedly been absconding since Chatterjee's arrest on July 12, was picked up from BB block in Salt Lake.
Chatterjee, the councillor of Ward 41 of the Bidhannagar Municipal Corporation, was arrested on extortion charges following chief minister Mamata Banerjee's intervention.
Police said Sen was Chatterjee's election agent in last year's Bidhannagar Municipal Corporation polls that were marred by widespread violence.
The police said Sen would roam around in Ward 41 looking for construction sites. He would ask the owner of a plot where construction had started to meet the councillor.
"If any owner refused or protested, Sen would unleash the might of the councillor's gang on him/her."