New Delhi: The Delhi Police has moved a Delhi court seeking permission to conduct polygraph test on three witnesses in the Sunanda Pushkar death case.

The police told a Patiala House court that Tharoor’s domestic help Narain Singh, driver Bajrangi and friend Sanjay Dewan have been found to concealing material facts about Sunanda’s mysterious death on January 17, 2014.

Calling them "suspects" in the case, police alleged that they have not disclosed several important issues related to her death.

Citing specific instances to claim that they are lying, the police told the court that the three were Tharoor’s close associates and were in present in Hotel Leela Palace just before Sunanda’s death.

Among the points raised by the police is the silence of the suspects about a power cut in room no. 345 just before the discovery of Sunanda’s death and, despite being there, they failed to explain the injury marks on Sunanda’s body.

Investigators have also found that repair work at Tharoor’s official residence – 97 Lodhi Estate – was over before January 15, the day Sunanda’s moved to the hotel. The suspects had claimed that she had moved to the hotel because of the ongoing repair work at their residence.

The police are also doubtful about their silence on Sunanda’s spat with Pakistani journalist Mehr Tarar and also about Sunanda’s threat to hold a press conference to “expose” Shashi Tharoor.

Sanjay Diwan’s role in the entire episode is also under the scanner as he has, as per the police, failed to explain why he cancelled his trip to Mumbai and came to Hotel Leela hotel. Diwan’s decision to send driver Bajrangi to bring Dr Rajat Mohan from distant Patel Nagar and not seek help from the hotel’s in-house doctor has also raised the police’s doubts over his role.

Responding to the plea, the court has summoned all three witnesses on May 20.

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 microblogging website Twitter over the latter's alleged affair with Tharoor.