Kolkata: In what seems like a clear case of honour killing, a man beheaded his younger sister in full public glare. The incident took place on Friday. 29-year old Mehtab Alam, a tailor by profession, allegedly beheaded Nilofer with a stroke of a sword.Reports indicate he then walked to the Nadial police station in South 24 Parganas district with his sister's head and the sword. The police said Mehtab asked to be charged and that he confessed to killing his sister for an extra marital relationship."Hussain told our stunned colleagues that he killed his sister because she was having an extra-marital affair," a police officer said. He said her body was dumped on a road in Ayubnagar.According to him, the young woman was in a relationship with a man. She later married another man but recently eloped with her paramour. "Hussain said he killed her to protect the honour of his family," police said. "He wanted to kill her paramour also."Alam has been remanded to judicial custody till December 22. He will make a confessional statement before a magistrate under section 164 of Criminal Procedure Code of India or CrPC on Monday.