Sunanda Pushkar, wife of Congress MP Shashi Tharoor, died of poisoning, say the police.
The questioning of two persons could be key to unravelling the alleged murder of Congress MP Shashi Tharoor's wife Sunanda Pushkar a year ago, sources have told NDTV.
A Special Investigation Team set up recently will question Rakesh Kumar, Mr Tharoor's personal assistant, and Sanjay Dewan, a close friend of the couple.
Both were present at the five star hotel suite in Delhi where Sunanda Pushkar, 51, was found dead on January 17 last year, and have been examined earlier.
Rakesh Kumar, say sources, bought tablets of Alprax, an anti-depressant, for Ms Pushkar but did not mention it when he was questioned by the police after the death.
The other witness, Sanjay Dewan, had called the doctor who declared Ms Pushkar dead. Sources say the police are investigating why Mr Dewan called a cardiologist, Dr Rajat Mohan, instead of taking Ms Pushkar to the hospital.
Mr Dewan, who is consul general of the Republic of Cape Verde, has reportedly told the police that the Tharoors were very happy together till December, 2013. On the evening she died, Mr Dewan reportedly cancelled his trip to Mumbai after learning that Sunanda was unwell, and came to the hotel to meet her.
Earlier this month, a murder investigation was launched against "unknown persons" by the police, who say Ms Pushkar died of poisoning, either given orally or by injection. Her viscera samples will be sent to a foreign lab to determine what sort of poison killed her.
In recent days, the police have questioned several people who were close to the couple; their domestic help, Narain Singh, was also interrogated for the third time.
The Congress leader could be questioned in the next few days, Delhi Police Chief BS Bassi told NDTV today.
In a letter to the police chief in November, which surfaced last week, Mr Tharoor had alleged that Narain Singh was beaten and forced to confess that he had killed Ms Pushkar along with the politician.
Mr Tharoor told reporters on Friday that he had written a second letter last week about the investigation to Mr Bassi.
Mr Bassi has refuted the allegations that his police force has made any attempt to frame Mr Tharoor.