Calcutta, July 6 :     The detective department today took over the probe of 48-year-old Leena Sen?s murder in her rented apartment in a high-rise off Ballygunge Phari in south Calcutta. Sen?s decomposed body was found in her flat on Saturday evening after officials from the Karaya police station broke open the door. The Karaya police had been handling the initial investigation since then. The post mortem by forensic experts yesterday confirmed that the assailant stuffed a piece of cloth down her throat and covered her mouth and nose, causing immediate death. The experts conducted detailed examinations to find out if there was any sexual assault and battery before the killing. Forensic experts who searched the apartment yesterday found two cigarettes stubs. Of the several glasses also found, one might throw up a finger print. Fluid from the decomposed body was collected off the kitchen floor where it was found by the police. The police also seized some letters and photographs from Sen?s flat. On the basis of these photographs and letters, some of her friends are being contacted for assistance in unravelling the mystery behind the murder. Photographs revealing her proximity to some Bengali film actresses were also found from the flat. Police have come to know by interrogating the gatekeeper and the caretaker of the multi-storeyed building that Sen had visited the flat on June 29 in a taxi around 2 pm. ?She entered the building in the taxi and then got down after paying the fare,? the gatekeeper, Shambhu Barua, recalled. ?Then she went up in the lift. It started raining after sometime. But I never saw her coming out of the flat that day,? he said. According to him, she was wearing a brown salwar-kameez. However, the police found her body without any clothes on Saturday. That she hired a cab on June 29 around 1.30 pm was also confirmed by her husband P.K. Sen who is the finance director of an advertising firm on Shakespeare Sarani. Deputy commissioner, detective department, Narayan Ghosh today said the police were cross-checking information before making a move in respect with what he described as a ?serious crime for passion?. ?We also spoke to her husband as well as friends at length during the day to find out clues which may lead to a breakthrough,? he added. Investigators also spoke to residents of Mainak apartment, but nobody could give any clues regarding the entry or exit of an assailant.