New Delhi, Oct 30 : The Swiss woman, who was found dead with her limbs and legs bound with chains near a school in West Delhi on October 20, was smothered as she suffered for 20 to 30 minutes before her death, sources said on Monday citing the autopsy report. According to sources, investigators initially believed that the victim, Nina Berger, had been strangled, but the preliminary findings of the autopsy report indicate that the cause of death was asphyxiation due to smothering. The sources also revealed that Berger had endured torture while inside a car, with a doctor's assessment confirming that she had been smothered with a plastic bag, her limbs bound with chains, as her desperate struggle damaged the car's seat cover. Doctors estimate that she had struggled for 20 to 30 minutes before breathing her last, the sources said. However, Deputy Commissioner of Police (West), Vichitra Veer, said the police are still waiting for the autopsy report and will be able to confirm the exact cause of death only after the receiving the report. The autopsy was conducted on October 28 after getting a go ahead from the Switzerland Embassy. Gurpreet Singh (33), the prime accused in the case, has claimed during investigation that he was in touch with foreigner women because of his father's gemstone and astrology business. According to the police, Singh claimed to possess expertise in "black magic, astrology, and mind powers". He told the interrogators that he utilised these 'abilities' to establish contact with Berger and persuade her to come to India. He frequently discussed his father's business, the art of healing through gemstones, and astrology techniques with the victim. Upon inspecting his phone, the police found that he frequently engaged in conversations with foreign nationals, offering his purported 'healing' services. During investigation, the police recovered various documents, including Begrer's passport and visa, from Singh's possession.A laptop, mobile phone and other documents, believed to be belonging to Berger, were also recovered from his possession which have been sent for forensic test. Meanwhile, the police are reviewing CCTV footage and interviewing hotel staff at two establishments in West Delhi where Berger stayed between October 11 and October 17. As per Singh's interrogation, he met Berger in 2021 during his visit to Switzerland, and soon their friendship developed into a close bond. Singh frequently travelled to Switzerland to be near Nina. Over time, he expressed his desire to marry her, but she had turned down his proposal. Berger came to Delhi from Zurich on October 11 and was staying in a hotel. However, as the interrogation of Singh continued, it became evident that he was trying to mislead the police. According to sources, the examination Singh's mobile phone revealed that he was in touch with at least a dozen women, all foreign nationals, an evidence that possibly links the case to the police's human trafficking theory. The police also seized over Rs 2 crore in cash from Singh's residence in Janakpuri. Further investigation revealed substantial financial transactions through Singh's bank account, leading the investigators to notify the Income Tax authorities. These high-value transactions and the unaccounted cash have raised suspicions that the case might be linked to human trafficking. /IANS