Burrabazar don Gopal Tiwari, an associate of several Trinamul leaders and the key accused in the violence that led to the shooting of a police officer on the day of the Calcutta Municipal Corporation elections, was arrested at a Baguiati hotel late on Thursday.

Tiwari was picked up from the VIP Road hotel around 10.30pm. "We have arrested Gopal Tiwari from a hotel in Baguiati. We are interrogating him. He will be produced in court tomorrow," joint commissioner (crime) Pallab Kanti Ghosh said.

Sources said Tiwari had checked into the hotel around 10pm. Sleuths had been preparing to arrest the accused since being tipped off that he had returned to the city a few days ago. Tiwari had apparently fled Bengal after the poll-day violence.

"We had information that he had returned to Calcutta a few days ago. This time we managed to get him through someone he trusted," an officer said.

Insiders in Lalbazar revealed the investigators had set a trap for Tiwari using a youth named Chhotu and called him to the hotel.

Hotel sources said a man clad in jeans and a black T-shirt had entered the hotel at 9.53pm and asked for the rate chart. Three minutes later Tiwari entered, in a yellow T-shirt. A small bag was all he was carrying.

Tiwari checked into the hotel in his name and took Room No. 304, which costs Rs 3,700 a night. He wrote his real address in the hotel register - 80/2, Pathuriaghata Street, Jorabagan, Kolkata, 700006 -and mentioned his actual cell phone number and email ID.

Sources said he had paid in cash and moved into his room when a team from the detective department arrived.

Trinamul leader Sanjay Bakshi had told The Telegraph a day after sub-inspector Jagannath Mandal was shot at on April 18: "Yes, I know him very well. He lives in Pathuriaghata and campaigned for the party nominee from Ward 21 (Tara Devi Purohit). He was with me when I addressed a pre-poll campaign in the Posta area."

Soon, pictures of Tiwari with several Trinamul leaders emerged.

It is because of his alleged Trinamul links that the police had initially appeared to be reluctant to arrest him.

They had apparently failed to locate an arms dump in the guard's room in Tiwari's Pathuriaghata apartment building while raiding the house on April 22.

On May 2, the police seized four guns, 100 bullets and explosives from the guard's room on the ground floor. Tiwari's apartment is on the second floor of the six-storeyed building on Pathuriaghata Street.

By the time investigators officially admitted his involvement in the shooting of the officer, he had fled, sources said.

The sub-inspector had told The Telegraph that he heard someone in an armed group say " Shaala police, maar (Bloody police, hit)" and then someone shot at him.

"He (Tiwari) was the man roaming in a vehicle through the day across the jurisdiction of my police station," Mandal, posted at Girish Park, had said.

Most of those arrested in connection with the case had said they were engaged by Tiwari. The police had apparently come close to arresting him on the night of the incident but could not go ahead because he was with a Trinamul leader.