Delhi police on Wednesday arrested Rohit Shekhar Tiwari's lawyer wife Apoorva on charges of his murder, citing a 'turbulent and unhappy' marriage as the motive, a senior police official said.

The officer said one of the reasons believed to be behind killing was Rohit's decision to give his share of property to his sister-in-law's son, he said.

Apoorva believed that Rohit's sister-in-law was the reason behind their turbulent marriage and held a grudge against her.

She tried to mislead investigators by claiming that she was getting intimate with Rohit and she might have accidentally pressed his neck, the official said, adding that the police are, however, not believing this theory.

The investigators said Apoorva changed her version of events often and whenever she was confronted with facts, she would weave her story around those facts.

Rohit, the son of late veteran politician N.D. Tiwari, was smothered to death on the intervening night of April 15 and 16, an autopsy report said.

Rohit and Apoorva married in May last year, after dating for a year. They had met through a marriage portal, police said.

Soon after their marriage, Apoorva left for her parental home in Indore, police said.

During questioning, Apoorva claimed she was the president of Indian National Trade Union Congress in Indore and had political aspirations but after getting married to Rohit in May, she realised he did not have much of a standing and his political career was not going anywhere.

Within 14-15 days of the marriage, she started staying away from him, the official said. 'Sometimes, she would stay at her parents' place and sometimes at a rented room she had in south Delhi before she got married,' the officer said.

'In July last year, while he was undergoing a bypass surgery, she had served him a legal notice saying she did not want to live with him. But both the families counselled them and advised them to give the marriage a second chance,' said the official, who was privy to the probe.

He said the problems were compounded because of a will that had been made before she got married to Rohit.

According to the will, the property was to be divided in a ratio of 60:40 between Rohit and his step-brother Siddharth.

Siddharth, who did not keep well, felt he would not live longer and had said he would give his share of property to the nine-year-old son of a relative of Ujjwala's first husband. Ujjwala is Rohit's mother.

Even Rohit had said he would give his share of property to the nine-year-old son of the relative, which angered Apoorva, the official said.

Police said they were suspecting her role since day one of the investigation, after Rohit's post-mortem report stated that he was 'smothered'.

'The suspicion on her arose because only three persons had access to Rohit's room on the first floor of the house, two servants and Apoorva. We confronted her with circumstantial evidence and she broke down on Wednesday and confessed,' the official said.

'On the night of the incident, the couple had a fight over a relative,' additional commissioner of police (crime) Rajeev Ranjan said. 'Rohit had been drinking all the way from Uttarakhand to Delhi and was not in a condition to resist' when she allegedly smothered him, Ranjan said.

Rohit, along with his mother and other relatives, had gone to Kathgodam in Uttarakhand to vote on April 10 and returned late on the evening of April 15, Ranjan said. He was drinking with his sister-in-law in his car, the official said.

After returning to Delhi, they had dinner with Ujjwala, Rohit's mother, and other family members around 11pm.

Later, his mother and other relatives returned to their Tilak Lane bungalow and his servants went to their rooms. Siddharth also retired to his room, the official said.

Around 12.45 am, Apoorva went to Rohit's room after watching TV. While they were in the room, the couple had an argument, he said.

Ranjan said in a fit of rage, Apoorva allegedly smothered Rohit.

Next day, around 2.30 pm, Rohit's mother came to his house and asked about him, another official said.

Apoorva told her that he was sleeping, so his mother did not disturb him as she knew that he had insomnia and he used to sleep late, Ranjan said.

Later around 4 pm, one of his servants noticed that he was not responding and was bleeding through his nose, the police said.

Rohit's mother was at Max Hospital in Saket when she received a call from home that he was unwell. She then took an ambulance that brought Rohit to the hospital.

He was declared brought dead by doctors and his body was sent for post-mortem to AIIMS.

The autopsy was done by a board of five doctors on April 17 and the report revealed that Rohit died of asphyxiation.