New Delhi: Congress MP Shashi Tharoor was today questioned by the Special Investigation Team (SIT) for the second time in last four weeks in connection with the mysterious death of his wife Sunanda Pushkar.

Tharoor was quizzed at the SIT office in Vasant Vihar in south Delhi on various aspects leading to Sunanda's death.

This is the second time that Tharoor faced tough questions by the Delhi Police which had earlier examined him on January 19.

"We have called him to know the certain details," a source said.

The police team probing the case has so far questioned at least 15 people. Tharoor, his staff members and close friends were among those quizzed by Delhi Police.

Pushkar's son Shiv Menon was quizzed by the SIT on February 5. Police sources had said that Menon was asked about the relationship between Tharoor and his Sunanda.

Former Samajwadi Party leader Amar Singh and senior journalist Nalini Singh, too, have been questioned by police.

52-year-old Sunanda was found dead in her suite at a five star hotel in south Delhi on the night of January 17, 2014, a day after she was involved in a spat with Pakistani journalist Mehr Tarar on micro-blogging website twitter over the latter's alleged affair with Tharoor.

Police had last month filed a murder case as part of its probe.