Radiation levels in Sunanda Pushkar’s viscera samples were “within the standard safety norms”, Delhi Police said today sharing the findings of an FBI report that virtually rules out the theory of ‘polonium poisoning’ having caused her death.

Delhi Police Commissioner BS Bassi said the report from Washington D.C.—based laboratory would soon be handed over to a medical board for examination before further action is taken in the high-profile case.

Meanwhile, sources in police said the Special Investigation Team (SIT) probing the case is likely to summon Pushkar’s husband and Congress leader Shashi Tharoor for questioning once again. They are also likely to seek court’s permission to conduct a polygraph (lie detector) test on the senior former Union minister.

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.

“I understand that the report has been received. The FBI lab had conducted analysis of various substances. And this should give an indication (as to the reason behind her death) once the doctors go through the report,” Bassi told reporters.

Asked about the radiation levels in the samples, the Delhi Police Commissioner said that it was “within the standard safety norms”. He added that the findings would have to be “correlated with the post-mortem report“.

According to sources, the eight-page FBI report, received around nine months after the samples were sent for examination, has named the alleged poison that led to Sunanda’s death two years ago.

The viscera samples were sent to the FBI lab in Washington DC in February 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.

Reacting to the developments, AIIMS forensic head Sudhir Gupta stuck to his opinion that poisoning was the cause of death.

However, he added that the “domain is much more large”, when specifically asked whether Polonium-210, a radioactive isotope, had caused the death.

“There are findings that confirm that the death was due to poisoning. We concluded by eliminating the other causes of her death,” Gupta said.

Sunanda was found dead inside her suite at a five-star hotel here on January 17 last year, a day after she was involved in a spat with Pakistani journalist Mehr Tarar on Twitter over the latter’s alleged affair with Tharoor, the Congress MP from Thiruvananthapuram.