For six months, a gang kept watch on a young polytechnic professor from Malda, learning about his ancestral property and daily routine before striking.

Tapas Kumar Mondal, 36, a resident of Mahananda Palli in Englishbazar, Malda, and a faculty member at Jalpaiguri Polytechnic, was kidnapped on September 8 while travelling by Padatik Express to Jalpaiguri.

Police rescued Mondal early on Wednesday from Tamluk in East Midnapore and brought him back to Malda on Wednesday night.

The meticulousness that went in planning the kidnap surprised cops.

On September 9, the abductors demanded a ransom of ₹3 crore by calling up the professor’s wife, Rakhi Mondal, who is also a government employee and mother of their two-and-a-half-month-old daughter.

The police traced the ransom calls to Tamluk in East Midnapore.

Following the lead, a special Malda team with the support of East Midnapore police, rescued the professor from a guest house in Tamluk early on Wednesday.

Six persons linked to the crime — Kartik Guchched, Riyad Sheikh, Suraj Sheikh, Kalu Sheikh, and Najimuddin Khan, all residents of Contai in East Midnapore, and Amrit Haldar, a neighbour of the professor in Malda — were arrested.

Findings of the police investigation have accused Kartik as the mastermind. According to cops, Kartik, along with his team, drew Amrit into the plan.

“Amrit, who had taken a rented house near the professor’s residence, allegedly kept close watch on Mondal’s daily movements and supplied details of his ancestral land and wealth to the gang,” said sources.

Cops said Amrit, out on bail in a previous case, had direct links with the abductors.

Saswata Jain, the additional superintendent of police, said that ransom calls made from Tamluk were a big clue that led investigators straight to the hideout.

“The abductors even made a video call to the professor’s wife, showing him at gunpoint and threatening to kill him if their rasom demand was not met,” Jain said.

The six accused were produced in Malda court on Thursday. Investigators sought seven days in police custody for them.

Jain said that custodial interrogation of the accused was essential to explore all angles of the crime.

The police are now probing whether the kidnap motive was confined to Mondal’s property or if other angles, including personal rivalry, played a role.

The abduction has left residents of Mahananda Palli shaken. On January 2 this year, Trinamool leader Dulal Sarkar was shot dead in the same neighbourhood.

Crushed to death

An elderly woman was crushed to death by a speeding state bus at Park Circus in Calcutta around 12.05pm on Wednesday.

Sursathiya Devi, 75, suffered several injuries and was declared dead at Calcutta national Medical College and Hospital, police said.

The bus was impounded and the driver detained.