Congress leader Shashi Tharoor’s wife Sunanda Pushkar, found dead in mysterious circumstances here in January last year, was poisoned to death, Delhi Police chief B.S. Bassi said .

“We have got the final medical report from AIIMS, and we have been told that it was an unnatural death… It was not a natural death,” Bassi told the media.

“She died due to poisoning. Whether the poison was given orally or injected into her body is being investigated,” he said, adding the report from the All India Institute of Medical Sciences was received Dec 29.

Bassi said the quantum of poison given to Pushkar, who was 52, had not yet been ascertained. “For that we will send her viscera abroad.”

A murder case had now been registered, the police chief said.

A special team has been formed to probe the case. This will be overseen by Deputy Commissioner of Police Prem Nath.

Asked why it took almost a year for the final medical report to come, Bassi said the interim report spoke of poisoning but did not say it was an unnatural death. “Even overdose (of medicines) can be poisoning.”

When IANS sought to know if Tharoor, a former central minister and now a Congress MP from Kerala, would be questioned again, he said: “We will do whatever is possible.”

Bassi said Delhi Police had sought the final medical report from AIIMS several times. “Now that we have got it, we are registering a FIR.”

Pushkar was found dead in a luxury hotel Jan 17, 2014, a day after she and Tharoor checked in because their house was allegedly getting painted. Both had been married twice earlier.

Tharoor was then the minister of state for human resource development in the Manmohan Singh government.

Tharoor was later named by Prime Minister Narendra Modi as one of the ambassadors of his Clean India campaign. After Tharoor praised the drive, a peeved Congress dropped him as one of its official spokespersons.

The medical investigation into Pushkar’s death took twists and turns.

The first autopsy report, submitted to a magistrate Jan 20 last year, had said that Tharoor’s wife died due to drug overdose. But it also reported a dozen injury marks on her body.

The final autopsy report that came out in July put the number of injury marks at 15. All the injuries were caused by blunt forces except one which was an injection mark.

Later, Sudhir Kumar Gupta, who headed the forensic team in AIIMS, alleged that he was pressured to show that Pushkar’s death was natural.

The AIIMS denied the allegation, and Gupta was removed from the post.

A day before she was found dead, Tharoor and Pushkar had issued a joint statement saying they were distressed by a row over some unauthorized tweets posted from their twitter account and that both were “happily married and intend to remain that way”.

The statement claimed that distorted accounts of comments allegedly made by Pushkar, alleging an affair between her husband and a Pakistani journalist, had led to some erroneous conclusions.