An element of mystery and doubt has been infused into the tragic death of Sunanda Pushkar, wife of Union minister Shashi Tharoor, with the post-mortem report saying that there was an injection mark on Pushkar's right wrist which caused her death.

All injuries on her body "were caused by blunt force, simple in nature and not contributing to death, except injury number 10, which is an injection mark," says the report.

Sunanda's body had 15 injuries, caused in 12 hours before her death. Injury number 12 was caused by a teeth bite. Injury number 10, an injection mark, remains a mystery, sources said.

A mild, foul-smelling gas emanated from her body during dissection, the report, signed by Dr Sudhir Gupta, said. It, however, doesn't spell out the details of injury number 10.

"Only the viscera report will reveal the nature of injection," sources said. The viscera report is likely to come out in March.

The Delhi police have written to the Central Forensic Science Lab last week seeking the report at the earliest.

An overdose of anxiety medicine Alprazolam was supposed to be the cause of her death so far. A sub-divisional Inquiry had also indicated this. But only "circumstantial evidences are suggestive of Alprazolam poisoning", the post-mortem report says.

Sunanda, 52, was found dead inside Leela Palace hotel in Delhi on January 17.