Sunanda Pushkar and Shashi Tharoor
Sunanda Pushkar had been poisoned, confirms Delhi Police. Pictured: Sunanda Puskhar Tharoor and Shashi Tharoor pose at the Indian F1 Grand Prix in Greater Noida on 27 October, 2013. SunandaReuters

There is a new twist in the mysterious death of Sunanda Pushkar, with Delhi police top cop hinting that radioactive susbstance Polonium-210 may have been used to kill her.  

"Polonium 210, a radioactive isotope, is suspected to be the poison that may have caused her death," said Police Commissioner B S Bassi. 

Sunanda Pushkar's autopsy report found traces of Polonium-210, which is a rare poison. Till now, only two previous murders have been reported in which Po-210 was found in the body of the deceased.

The first one was the famous Palestinian leader Yaseer Arafat, according to researchers from Lausanne University Hospital's Institute of Radiation Physics in Switzerland.

The report, which has been published by Al Jazeera, said that the Swiss scientists found that "the results moderately support the proposition that the death was the result of poisoning with polonium-210".

In the second case, a former Russian agent Alexander Litvinenko was allegedly poisoned by two Russians, who put Po-210 into the coffee that Litvinenko drank.

Chemistry World, a journal published by the Royal Society of Chemistry, notes that polonium is the source of Polonium-210, or Po-210, which "is one of 25 radioactive isotopes of polonium - it decays to lead by alpha particle emission, with a half life of 138 days."

The silver-coloured metal discovered by Marie and Pierre Curie in 1897 is also extremely hard to detect. A report in The Guardian following Litvinenko's death by Po-210 noted:"It is extremely hard to detect. Scientists only identified it in Litvinenko hours before his death."

"A former FSB officer, and teetotaller, Litvinenko was a fitness fanatic. Doctors say it was only because he was in such good shape that he lasted so long. If he had died sooner, the cause of death would probably never have been uncovered."

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