With the severed head of his sister, Nilofer Biwi in his hand, 29-year-old Mehtab Alam walked into Nadial police station and surrendered along with the sword yesterday.
He confessed to the crime and was arrested, police said.
Despite being married and having two children, Nilofer had eloped with a rickshaw puller following which her parents had lodged a missing diary with the police.
Police said when Alam, a garment trader, found out that his sister was staying with a rickshaw puller he went to his place and dragged her out on the road in full public view.
In front of the crowd, he chopped off her head with the sword.
Alam's family members came rushing to the police station as they were caught unaware of his motives, Deputy Commissioner of Police (Port division) Mehboob Rehman told PTI.
"It was not the decision of the family to kill her. The brother had lost his temper over his sister and so he had unilaterally decided to kill her," he said.
Alam was today remanded to judicial custody till December 22 after his production in Alipore court.