Calcutta, July 28 :     Nearly four weeks after Leena Sen was found murdered in her apartment in south Calcutta, detectives today arrested her husband and claimed they had made a breakthrough. The finance director of an advertising firm, Leena?s husband P.K. Sen was arrested from his Shakespeare Sarani office early this evening. He will be produced in court tomorrow and has been charged under Section 302 of the IPC. On July 3, residents of Mainak Apartments, a multi-storeyed building in Ballygunge, complained of foul smell emanating from a flat on the ninth floor. Police officers of Lalbazar?s detective department broke into the flat to find a body without any clothes propped up against a wall in the kitchen. The post-mortem report said a piece of cloth had been thrust down Leena?s throat, choking her to death. The post-mortem, however, revealed that she had not been raped. Detectives conjectured that the killer had stripped her to throw them off-scent. Close friends of the Sens then disclosed that the couple was estranged and husband and wife led separate lives. Pursuing several avenues, detectives narrowed to just one motive behind the grisly murder. They felt that it was a crime of passion. Revenge may have driven the killer. In the next few weeks, they interrogated several friends, relatives, the driver and P.K. Sen. Deputy commissioner of police, detective department, Narayan Ghosh, today said the driver Sheikh Ibrahim told interrogators that he drove P.K. Sen to Leena?s flat in the afternoon on June 29. The Sens home is on Prince Ghulam Mohammed Shah Road. Investigators said Leena had gone to Mainak Apartments that day in a taxi. Gatekeeper Sambhu Barua and caretaker Dilip Chatterjee saw her entering the flat around 1.30 pm. Ibrahim said he drove P.K. Sen in a steel colour Maruti Esteem around 3 pm. The liftman, too, corroborated that P.K. Sen entered Leena?s flat and that to the best of his knowledge he was the only person who had visited her that day and left after a while but alone. The liftman, gatekeeper and caretaker said they did not see Leena leave the flat after June 29 and nor did anyone visit her. On June 30, P.K. Sen lodged a diary with the Jadavpur police station, saying his wife was missing since June 29 afternoon. Deputy commissioner Ghosh said: ?On the basis of specific circumstantial evidence we believe that P.K. Sen had a role to play with this. It was a crime of passion and revenge.? ?There are certain specific details on the motive behind the killing, but we will not disclose them in the interest of the case,?? Ghosh added. Man lynched Chandan Mukherjee, 28, was lynched at Lakshkantapur in the Mandirbazar police station area last night. Police said he was caught by residents while stealing wires from the WBSEB godown along with four aides. While three of his accomplices fled under cover of darkness, Mukherjee was caught and lynched. Racket in stolen cars busted The North 24- Parganas police today unearthed a racket in stolen cars after a raid conducted in Habra. Three Ambassadors and a motorcycle waylaid from Ultadanga and Salt Lake areas have been recovered. ?We have arrested six persons, including the kingpin. They have told us the location of six more cars,? additional superintendent of police Pravin Kumar said. More arrests are likely, he added. Train back on track The Howrah-Rourkela Shatabdi Express, which had been cancelled after a derailment on June 7, would resume from August 9. The services were suspended for repairs to the specially-made bogies.