A carpenter has been arrested for the murder of homemaker Pratima Maity, whose body was found tied to a bed-frame at her Girish Park home on Monday afternoon.

Police said the accused, Alam Ali, 48, was in a relationship with the woman and had got engaged in a sexual act with her on Saturday night.

The accused is said to have told the police that the woman had demanded Rs 50,000, threatening to scream if he refused to pay. Ali apparently covered Pratima's mouth with a pillow in an attempt to silence her, resulting in her death. He is also said to have told the police that he had used a piece of cloth to strangulate her.

"Alam Ali has confessed to his crime. He is claiming that the victim blackmailed him for money after a sexual act and she died when he tried to suppress her screams," joint commissioner (crime) Pallab Kanti Ghosh said.

The head injuries Pratima had suffered were apparently caused when she accidentally hit her head against a wall while trying to resist Ali's attempt to smother her.

Ali was held at his home in Daspur village - where Pratima's parental home is located, too - in West Midnapore early on Wednesday.

The police have found that Ali had met Pratima over a year ago at her niece's wedding in the village. Pratima's phone call details, sleuths said, revealed that she had been in regular touch with Ali.

"The accused is claiming this was the first time he visited her house. This we are not sure of. But what is clear is that he had been in touch with the victim for over a year. He apparently came to help her sell her old furniture as she had been planning to shift to Gujarat, where her younger son lives," said an officer.

Pratima shared a strained relationship with her husband Dilip, a costume jewellery trader in Hyderabad. The couple's elder son and his wife live in Hyderabad, too.

Ali apparently had come to Pratima's Banarasi Ghosh Street house around 2pm on Saturday. "He left for Sealdah to look for shops where he could sell old furniture and returned around 9.30pm. Thereafter, he said, he got engaged in the act, during which she threatened to scream," said a sleuth.

"Though the post-mortem report suggests the victim was smothered to death, the accused has said he had also throttled her. We have sought a second opinion about the post-mortem findings," an officer said.