Rohit Shekhar Tiwari's post-mortem report has revealed "unnatural death"

Highlights Rohit Shekhar Tiwari, 40, was said to have died due to a cardiac arrest

His post-mortem report reveals an "unnatural death"

He had fought a long legal battle to prove that he was ND Tiwari's son

Rohit Shekhar Tiwari, the son of former Uttar Pradesh chief minister and Congress stalwart ND Tiwari, did not die a natural death and was most probably killed by being smothered with a pillow, sources in the Delhi Police have said, after a post-mortem was conducted.

The post-mortem report reveals "unnatural death". Rohit Tiwari, 40, was said to have died on Wednesday due to a cardiac arrest.

The investigation has been transferred to the Crime Branch of the Delhi Police which has registered a case of murder.

Crime Branch officials visited Rohit Tiwari's house yesterday and questioned his family members and domestic helps. His wife Apoorva is currently not in Delhi. A forensics team too visited the house.

Police sources say there are seven CCTV cameras - of which two don't work - in Rohit Shekhar Tiwari's house in Defence Colony, a posh residential area in south Delhi. They say Rohit Tiwari had gone to Uttarakhand to vote on April 12 and returned on the night of April 15. He could be seen on CCTV taking support of the wall while walking in an inebriated state, police sources added.

The next day, Rohit's mother Ujjwala Tiwari was in Max Hospital for her treatment when she received a call from home that he was unwell and bleeding from his nose. She then took an ambulance that brought Rohit to the hospital.

At that time of the phone call, Rohit Tiwari's wife Apoorva, his cousin Siddharth and domestic helps were at home, police sources said.

A senior police official had on Wednesday said Rohit Shekhar Tiwari was declared brought dead at Max Hospital, adding no external injuries were seen on his body.

Rohit Shekhar Tiwari had fought a six-year-long battle in court to prove that he was ND Tiwari's son.

ND Tiwari had refused to give his blood sample for a DNA test in 2012. He, however, relented later.

In 2014, the Delhi High Court declared ND Tiwari as the biological father of Rohit Shekhar, after the senior leader accepted that he was indeed his son.

The court also restrained Mr Tiwari from denying in public that Mr Shekhar was not his son.

The same year, ND Tiwari, aged 88, married Rohit Shekhar Tiwari's mother.

After ND Tiwari's death on his 93rd birthday last year, Rohit Shekhar Tiwari had demanded that the government at the centre, in Uttar Pradesh and in Uttarakhand build memorials and name schemes in the memory of his father.