Sunanda Pushkar was found dead inside her hotel room in Delhi in 2014.
Over two years after Sunanda Pushkar, wife of Congress leader Shashi Tharoor, was found dead in her suite at a luxury hotel in Delhi, a police team is in the US to meet the Federal Bureau of Investigation or FBI for answers.
Sources say the Special Investigation Team inquiring into the death has asked the FBI to specify the cause of Ms Pushkar's death.
An FBI report had last year tested samples and ruled out the possibility of poisoning by a radioactive substance.
51-year-old Ms Pushkar was found mysteriously dead in January 2014, days after her fight on Twitter with a Pakistani journalist she suspected was having an affair with her husband.
For a year, her death was considered a case of suicide, but last year, the police claimed she was poisoned and registered a murder case against unknown persons.
After a panel of doctors from the AIIMS hospital in Delhi said the poison could not be detected in Indian labs, Ms Pushkar's viscera samples were sent to the FBI lab in Washington in February last year.
In November, the FBI told the police that Ms Pushkar did not die due to poisoning by polonium or any other radioactive substance, as had been suspected.
The police have not named any suspects in the case but has questioned Mr Tharoor, 60, multiple times. It has also conducted polygraph tests on six people including his domestic help.
Sources say the investigation team's visit to the US signals that the case may take a significant turn in the coming days.