A woman who pleaded guilty to killing her fiancé by sabotaging his kayak claims she did so because she grew tired of his 'sex demands'.

Latvia-born Angelika Graswald, 37, pulled the drain plug from Vincent Viafore's boat, which led to him drowning in the Hudson River in New York in April 2015.

Investigators became suspicious of Graswald after she was seen posting videos on social media of her doing cartwheels, and even a picture of herself in a kayak with the comment: 'If only I could have paddled harder, dammit.'

Graswald, who was released from prison just six weeks after she was convicted, admitted in a 11-hour interview with authorities that she grew tired of sexual demands.

Angelika Graswald, 37 (center, in court, July 2017) , who pleaded guilty to killing her fiancé, 46-year-old Vincent Viafore, by sabotaging his kayak claims she did so because she grew tired of his 'sex demands'

Some of these demands included requests for threesomes, which never happened, but Graswald (pictured, left, with Viafore) said would often be fought about. She admitted that she felt trapped in the relationship and sometimes wished he was dead

Graswald pulled the drain plug from a kayak (pictured) that she was on with Viafore, which led to him drowning in the Hudson River in New York in April 2015

Some of these demands included requests for threesomes, which never happened, but Graswald said would often be fought about.

She also admitted that she felt trapped in the relationship and sometimes wished he was dead, saying: 'I wanted to be free'.

Another motive was the $250,000 that she stood to gain from two insurance policies.

When asked if she felt relieved that he was dead, she answered: 'Yes.'

Investigators asked her whether she had removed the plug because she wanted Viafore, 46, to die.

'Yes, at some point, yes,' she replied.

When asked if she felt relieved that he was dead, she answered: 'Yes.' Investigators asked her whether she had removed the plug because she wanted Viafore (pictured, left, with Graswald) to die. 'Yes, at some point, yes,' she replied

The bride-to-be (pictured, with Viafore) admitted to hastening her fiance's demise by pushing a floating paddle away from him

Graswald (pictured, center, July 2017) pleaded guilty to a charge of criminal negligent homicide in the death of her fiancé.

Graswald pleaded guilty to a charge of criminal negligent homicide in the death of her fiancé. In exchange for agreeing to plead guilty to that charge, prosecutors dropped the more serious charges of second-degree murder and manslaughter.

On November 8, she was sentenced to one-and-one-third to four years in prison, but was released after just six weeks because the two-and-a-half years she spent locked up in an Orange County jail after her April 2015 arrest counted towards the sentence.

Following her release, Graswald will spend 16 months being supervised in a women's halfway home.

At the end of that, a judge may decide to deport her back to her native Latvia, which she left in 2000 after she came to the US as a nanny.

The victim's family members previously slammed Graswald's sentence as an injustice.

In exchange for agreeing to plead guilty to that charge, prosecutors dropped the more serious charges of second-degree murder and manslaughter (Pictured, Graswald, center, July 2017)

On November 8, Graswald (pictured, December 2017) he was sentenced to one-and-one-third to four years in prison, but was released after just six weeks because the two-and-a-half years she spent locked up in an Orange County jail after her April 2015 arrest counted towards the sentence

Following her release, Graswald (pictured, December 2017) will spend 16 months being supervised in a women's halfway home. At the end of that, a judge may decide to deport her back to her native Latvia, which she left in 2000 after she came to the US as a nanny

Graswald and Viafore went kayaking on a choppy Hudson River near Bannerman Island on April 19, 2015.

Prosecutors said Viafore's kayak started sinking after Graswald secretly removed a drain plug.

The bride-to-be admitted to hastening her fiance's demise by pushing a floating paddle away from him.

Graswald was originally charged with second-degree murder and manslaughter, but took a plea deal in July, just weeks before her murder trial was set to start.

In a statement through her lawyer after the sentencing, Graswald said: 'I loved Vince very much and miss him terribly.

'I don't believe I was treated fairly. This entire process was incredibly one-sided and unjust.'

But the victim's mother, Mary Ann Viafore, said she doesn't believe a word Graswald says.

'Four years for taking someone's life? No way,' she told CBS New York in November. 'My son was a good man and everybody loved him and we miss him very much. I don't ever want to see her again if I don't have to.'