The Delhi Police on Monday filed a charge sheet in a court accusing Tharoor of abetting the suicide of Pushkar. Tharoor is the only person who has been arrayed as an accused in the case.
The police in its charge sheet, which runs into around 3,000 pages, has also alleged that Tharoor had subjected his wife to cruelty.
The police filed the charge sheet in the mysterious death of Pushkar before Metropolitan Magistrate Dharmendra Singh, who will consider it on May 24.
It also urged the court to summon Tharoor as an accused.
Pushkar was found dead in a luxury hotel room on the night of January 17, 2014.
The Congress leader has been charged under sections 498 A (husband or his relative subjecting a woman to cruelty) and 306 (abetment of suicide) of the Indian Penal Code.
The charge sheet, which includes several annexures, said that Pushkar died within three years, three months and 15 days of her marriage with Tharoor, who is the Lok Sabha MP from Thiruvananthapuram.
The couple had entered into wedlock on August 22, 2010.
Pushkar was found dead in the suite of the South Delhi hotel on January 17, 2014. The suite was sealed that night itself for investigation. An FIR was registered by Delhi Police on January 1, 2015 against unknown persons under IPC section 302 (murder).
Reacting to the development, Tharoor termed the charge sheet as "preposterous charge" and said he intends to contest it "vigorously".
"I have taken note of the filing of this preposterous charge sheet &intend to contest it vigorously. No one who knew Sunanda believes she would ever have committed suicide, let alone abetment on my part," the Thiruvananthapuram MP wrote on Twitter.
"If this is conclusion arrived at after 4+ yrs of investigation it does not speak well of the methods or motivations of the Delhi Police. In oct 17, the Law Officer made a statement in the Delhi High Court that they have not found anything against anyone & now in 6 months they say that I have abetted a suicide. unbelievable," he said.
The Delhi Police said that the charge sheet filed was finalised on the basis of "medico-legal and forensic evidence".
"On the basis of medico-legal and forensic evidence analysed during investigation as well as opinion of psychological autopsy experts, the charge sheet was filed. The matter is sub judice," said a Delhi Police spokesperson told PTI.
(With inputs from PTI)