A magistrate looking into the death of Ms Sunanda Pushkar, the wife of junior minister Shashi Tharoor, says further investigations are needed to determine if it was suicide or murder.
It is understood a medical autopsy has ruled that she was "poisoned" by an overdose of drugs.
Sub-divisional magistrate Alok Sharma, who received the autopsy on Monday, has asked the Delhi police to look at both the suicide and murder angles, the Press Trust of India reported. He has also questioned Mr Tharoor and other family members and friends.
Ms Pushkar's body was discovered by Mr Tharoor, 57, junior human resources development minister, when he returned to their luxury hotel suite after a Congress party meeting last Friday.
When contacted, police spokesman Rajan Bhagat said: "We will examine the SDM (sub-divisional magistrate) report and then take a decision for the next course."
Under India's Criminal Procedure Code, a probe by a magistrate is the first step if the case involves suicide by a woman married for less than seven years.
Ms Pushkar and Mr Tharoor tied the knot in 2010 but rumours of problems in their marriage started circulating last year.
The couple were spotted together in recent months, celebrating the New Year in the southern state of Goa.
But in a sign that all was not well, two days before her death, Ms Pushkar took to Twitter to accuse Pakistani journalist Mehr Tarar of stalking her husband and her husband of adultery.
She later issued a joint statement with her husband maintaining that they were happily married and blamed the controversy on unauthorised tweets.
The mystery surrounding her death deepened when doctors conducting Saturday's autopsy described her death as "sudden and unnatural".
They also said they had found "certain injury marks" on her hands, though they clarified these had nothing to do with her death.
While the autopsy has suggested that she died from drug overdose, doctors said only a police investigation would determine if it was suicide, murder or accidental.
"Ultimately, the medical autopsy is just one part of a criminal investigation. The autopsy has to be interpreted in the given context. There are so many other corroborative evidences," Dr Amit Gupta, a professor of surgery from the All India Institute of Medical Sciences, told The Straits Times.
"They (the police) have to build a case around it."
The police are expected to move quickly, as home minister Sushil Kumar Shinde has asked investigators to fast-track the probe. Mr Tharoor himself asked for a speedy probe.
On Sunday, he said he was "horrified to read the reckless speculation" rampant in the media and wanted the truth out as soon as possible.
A former United Nations diplomat who entered politics five years ago, he has been looking at running for the parliamentary seat of Thiruvananthapuram in the southern state of Kerala. Elections are due within five months.
In 2009, Mr Tharoor won by a large margin. But the death of his wife under mysterious circumstances after a very public Twitter spat is expected to have an impact on his political career.
On Monday, Mr Tharoor said his wife spoke her mind. "She had a great sense of style and was an amazing cook: a feisty woman full of ambition and ideas," he was quoted as saying.
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