'Dangerous chemical' may have killed Sunanda: FBI

The case of sensational death of Sunanda Pushkar, wife of Congress leader Shashi Tharoor, reached a new stage with the FBI endorsing the AIIMS report of poisoning as the cause and also saying that a "dangerous chemical" was present in her body that may have killed her.

Disclosing the receipt of the AIIMS report analysing the FBI conclusions, Delhi Police Commissioner B S Bassi told the media that Sunanda's death was not natural but ruled out the presence of radioactive material in her viscera.

Sudhir Gupta, head of AIIMS Forensic Science department, said the FBI report also said the death was due to poisoning as was concluded by the AIIMS.

"One thing is clear that the death was not natural. It was unnatural as per our investigation till now and evidence collected so far. I can say that with certainty," Bassi told reporters here.

He further said, "I have no knowledge on the mention of any dangerous chemical in the FBI report. The FBI report had said none of the samples contained any radioactive material. I can confirm there's no radiaoactive material but certain other findings are there. We had given the entire report to the medical board which has examined and gave us a report."

Gupta said FBI has not ruled out completely the presence of radioactive substances in viscera samples. "But due to degraded condition of the viscera samples, they could not read the intensity of the substances."

He said the FBI analysis of stomach, spleen, liver, kidney and urine has endorsed the cause of death saying that "the same poison is present in all the viscera".

"It also endorsed the AIIMS post-mortem report saying cause of death is poisoning. However, FBI additionally mentioned the presence of a dangerous chemical which may be cause of the death if given injectable," Gupta said.

In January last year, Delhi Police had registered a case of murder in connection with the death of Sunanda. An AIIMS medical board had found poisoning as reason for her death following which the police had sent her viscera samples to an FBI lab in Washington last year.

There was earlier speculation that Sunanda may have died as a result of poisoning through radioactive substances.

The FBI had sent its report to Delhi Police two months ago. The report said the radiation levels in Sunanda's viscera samples were "within the standard safety norms" besides mentioning other details.

As police could not firm up about cause of the death based on the FBI report, they requested a medical board of AIIMS to analyse the contents of the report.

Bassi said the high-profile case will be taken to its logical conclusion soon and all possible angles are being examined.

"The medical board has submitted to us 11-page report with 32 pages of annexures which are to be examined. They have mentioned about certain conclusions which are now to be investigated," he said.

51-year-old Sunanda was found dead at a suite in a five-star hotel in South Delhi on the night of January 17, 2014, a day after her spat with Pakistani journalist Mehr Tarar on Twitter over her alleged affair with Tharoor.

"FBI report had said that radioactive levels were within acceptable range. It had ruled out the radioactive angle. Certain other chemical compounds were found by the FBI lab. The medical board has given certain conclusions. We will investigate those," Bassi said.

The Delhi Police Commissioner today held a meeting which was attended by the Special Investigation Team (SIT) probing the case. Special Commissioner of Delhi Police (Law and Order) Deepak Mishra briefed about all related angles in the case.

"Have been told that Medical Board's advice in late Sunanda's case has been received," Bassi tweeted earlier. He added Mishra was reviewing the progress in the case.

The investigators have so far conducted polygraph test on six persons, all prime witnesses in the case, including Tharoors' domestic help Narayan Singh, driver Bajrangi and Sanjay Dewan, a close friend of the couple. Tharoor was not subjected to the test but was questioned thrice in the case.

The FBI report had ruled out the theory of the variant of a radioactive element named Polonium having caused Sunanda's death, noting that radiation levels in her viscera sample were within the standard safety norms.

In January last year, police had claimed that Sunanda was poisoned, and registered a murder case against unknown persons. Three others -- S K Sharma, Vikas Ahlawat and Sunil Takru, had also undergone the polygraph test.

The police team probing the case has so far questioned at least 15 people. Tharoor, his staff members and close friends were among those questioned by Delhi Police. Sunanda's son Shiv Menon was quizzed by the SIT on February 5 last year.