After AIIMS' Medical Board sent its observations on the final viscera report of Sunanda Pushkar's death, BS Bassi on Friday said that evidence point that her death was unnatural.

"We are studying the report, once we analyse the content we will continue with our investigation. All conclusions shall be examined, and then decide future course of action," said Bassi.

He further added, "As far as evidences are concerned until now, Sunanda Pushkar's death was unnatural."

"The FBI analysis endorsed the cause of death saying that the same poison is present in all the viscera. It additionally mentioned the presence of a dangerous chemical which may be cause of the death of given injectable," reported ANI quoting sources.

Sunanda was found dead inside her suite at a five-star hotel here in January 2014, a day after she was involved in a spat with Pakistani journalist Mehr Tarar on Twitter over the latter's alleged affair with her husband Shashi Tharoor, the Congress MP from Thiruvananthapuram.

Her viscera samples were sent to the FBI lab in Washington DC in February last year to determine the kind of poison that killed her after an AIIMS medical board identified poisoning as the reason behind her death but did not mention any specific substance.

The FBI report had virtually rules out the theory of 'polonium poisoning' having caused her death. However, after Delhi police failed to draw any conclusion on basis of the findings, the report was handed over to a medical board for examination before further proceedings in the high-profile 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 has been questioned in the case.

With agency inputs