Bandel: A help hired one-and-a-half-years ago had killed retired university professor Sulekha Mukherjee with the help of three others, police said.

Madhavi Karmakar, the help, her husband Bishu, mason Subal Karmakar, and Gorkha Paswan, known in the locality as a ruffian, have been arrested on the charge of murder. The police said the four had ganged up to kill Sulekha to grab her jewellery and money.

The accused have been picked up from various pockets in Bandel's Kazidanga, where Sulekha lived.

A sickle that the police said was used to slit the victim's throat has been seized.

The police said they had come to know about the plot while questioning Gorkha in connection with another case of dacoity.

Sulekha, 66, who had retired as head of the mathematics department at Kalyani University, was found murdered in a ground-floor room of the two-storeyed house in Kazidanga on October 26. A piece of cloth was tied around her mouth. Her throat was slit and the head bludgeoned.

The day the body was found, Madhavi had said she was the first to raise the alarm around 6.30am after Sulekha failed to open the door of the house.

In reality, the police said, Madhavi had pressed the door bell around 4.30am on October 26. Sulekha opened the door and returned to her bed.

"Madhavi, and the three others, entered the house and started looking for cash and jewellery. When the victim woke up and started screaming, she was murdered," an officer said.

"Subol slit her throat with a sickle and left a knife beside the body to mislead the police," said Atul V., additional deputy commissioner, Chandernagore commissionerate. "We are trying to find out how much cash and jewellery the gang had taken away."

A preliminary probe has revealed that Madhavi, who was hired by Sulekha one-and-a-half-years ago, knew that the victim had some cash with her after she returned from a holiday in the Northeast with her two sisters.