The team is likely to return by the end of the week. The US agency has already given its report which will be discussed with a medical board, a senior police officer said.
It is just a routine exercise to bring back the samples lying with the FBI lab. The team will also seek details on some points mentioned in the US probe agency's lab report, 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, the Congress MP from Thiruvananthapuram in Kerala.
Delhi Police had in January last year registered a case of murder in connection with Sunanda's death. An AIIMS medical board had earlier found poisoning as reason for her death following which the police had sent her viscera samples to the FBI lab in the US.
Several persons including Shashi Tharoor have been questioned in connection with Sunanda's death. The police have also conducted polygraph test on six persons, all prime witnesses in the case, including Tharoor's domestic help Narayan Singh, driver Bajrangi and Sanjay Dewan, a close friend of the couple.
In February, Tarar was questioned about her relation with the Congress leader and his wife, her fight with Sunanda over Twitter, and other issues revolving around Sunanda's death.
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