Sheela Roy?s death wasn?t an accident or a suicide. It was a hired hit, commissioned by her husband.

The investigation into the death of Sheela Roy, a schoolteacher who was five months? pregnant, revealed on Thursday that husband Tarun Roy, also a schoolteacher, had hired a killer to eliminate his wife.

The revelation comes one-and-a-half months after the arrest of Kaushik Biswas, who had been engaged by Roy, a resident of Barasat?s Hridaypur Park, to kill the 27-year-old.

?Apparently, Biswas had been paid an advance of Rs 25,000,? said an officer of Barasat police station.

Sheela, who was run over by a train at Ultadanga station on January 13, was at first believed to be the victim of an accident, and then, a suicide. But the trail took a turn after a week, with the arrest of Biswas, who claimed to have witnessed the ?accident?.

Police found Biswas?s role suspicious. Though apparently a stranger, he had been by her relatives? side for three days ? from Sheela?s admission to Nilratan Sircar Medical College and Hospital to the post-mortem.

?Biswas told police that he had been waiting for a train when the mishap occurred. But now, we realise he was trying to mislead us by providing false information. Roy had engaged him to do just that,? said an officer of Barasat thana.

?The incident seems to be a cold-blooded murder,? said another officer of the police station. Roy had chalked out the plan well and had almost convinced sleuths that the death was an accident or suicide.

Suspicion about Biswas grew when he tried to persuade Sheela?s relatives not to lodge a complaint against Roy and his family.

?After hearing his contradictory statements during interrogations and going through his notebook, we were sure that he was involved in the murder. Roy?s telephone numbers and the direction to his house were found in the notebook. Immediately after Biswas?s arrest, Roy surrendered in court,? said an officer.

Police are now awaiting Roy?s itemised cell phone records to ascertain how many times he had contacted Biswas before Sheela?s death.

Roy was under police scanner from the beginning.

A week before her death, Sheela, who was a teacher of a girls? school in Maniktala, had lodged a complaint with Barasat police station, giving the details of the abuse she faced at her in-laws?.

On January 13, though Roy was informed about Sheela?s death around 11 am, he reached the hospital around 6 pm. ?We found out that he had spent the time in Sheela?s room tampering with evidence related to his torture,? the officer added.

A hunt is on to track down the other accused ? Roy?s parents Dinanath and Bibha, and sister Madhuri, said Subhankar Chatterjee, sub-divisional police officer, Barasat.