In October 2014, a team of three doctors from the All India Institute of Medical Sciences, headed by Dr Sudhir Gupta, had said that Sunanda Puskhar had been poisoned. Their report however did not name the specific poison or chemical that caused the death. Instead, it listed a number of poisons that cannot be detected in Indian labs.

These include thallium, polonium 210 (a radioactive substance of which a few milligrams is lethal), nerium oleander, snake venom, photolabile poisons and heroin. Polonium 210 is the same substance that was used on Kremlin critic and ex-spy Alexander Litvinenko and possibly Yasser Arafat and is extremely hard to detect.

Today, Delhi police commissioner BS Bassi said Pushkar's viscera will be sent abroad for a probe since some of these substances cannot be detected in Indian labs.