In fresh details emerging in the sensational death of Sunanda Pushkar, her husband and Congress MP Shashi Tharoor had accused Delhi Police of "repeatedly physically assaulting" and intimidating his domestic help into "confessing" that they both murdered her. In a letter written to Delhi Police Commissioner B S Bassi on November 12 last year, he had said that "such conduct" by one of the Delhi Police officer against his domestic help Narayan Singh was completely unacceptable and illegal. Tharoor said he and his staff had "cooperated fully" with the police probing the case. "I was therefore shocked and appalled to learn that in the course of the 16-hour interrogation conducted by four Delhi Police officers on Friday (7\/11\/14) and again during the 14- hour interrogation on Saturday (8\/11\/14), my domestic helper Narayan Singh was repeatedly physically assaulted by one of your officers. "Worse, the officer used the traumatic physical assault to try and intimidate Narayan into 'confessing' that he and I murdered my wife," Tharoor said in the letter. Tharoor also referred to his telephonic conversation with Bassi on November 8 when he had expressed his concerns about the alleged police action. "As you graciously agreed, such conduct is completely unacceptable and illegal. It also ammounts to the use of physical coersion in the attempt to frame an innocent man. I would request you to take immediate and appropriate action against such unlawful misconduct of the officer concerned," he said. Delhi Police had yesterday registered a murder case into Sunanda's death under section 302 of the IPC on the basis of an AIIMS medical report. The report had concluded that her death was unnatural and due to poisoning, but nobody has been named as a suspect as yet. The FIR was filed against unknown persons. 51-year-old Sunanda was found dead in a five-star hotel in the national capital on January 17 last year. Asked about Tharoor's allegations, Bassi said, "if there is anything of that sort, we will definitely look into it." In the letter, Tharoor had reiterated that he has "complete trust and faith" in the Delhi Police and that he was committed to fully cooperate with the investigations to ensure the timely completion of the inquiry. "My staff and I have always made ourselves available for any kind of inquiry and investigation, but the recent behaviour of the officers towards my staff is a matter of serious concern to any law-abiding citizen. "Please look into the matter personally and ensure that the unvarnished truth comes out in this case. My family and I are eagerly waiting to see the outcome of the inquiry conducted by the Delhi Police," Tharoor had said in the letter. In a statement, Tharoor had yesterday said he was "stunned" over Delhi Police registering a murder case into Sunanda's death and sought "full information" from the investigators on the basis of which the action was taken. The investigators have decided to send her viscera samples to a laboratory either in Britain or the US to identify the poison including whether it could be radioactive isotopes that cannot be detected in Indian labs. Sources said the SIT is likely to question Tharoor, his relatives and personal staff along with the employees of the five-star hotel where she was found dead on January 17 last year. The investigators said a case of murder was registered after an AIIMS medical report said that Sunanda's death was unnatural and was caused due to poisoning.