The father of two children murdered by his ex-wife said he felt 'much relief' after learning her request for parole had been denied.

David Smith was campaigning against Susan Smith's bid for freedom yesterday, which came 30 years into her life sentence for killing their sons Michael, three, and Alex, 14 months.

Mr Smith told NewsNation's Ashleigh Banfield that he welcomed the unanimous verdict of the South Carolina Department of Probation, Parole, and Pardon Services board.

'It was, like they say, lifting the world off my shoulders,' he said. I could just let out a sigh.'

Smith was jailed for life over the 1994 murders. She strapped her two children into car seats before allowing them to roll into a lake to drown.

The child killer then claimed she was the victim of a carjacking and blamed an unidentified black man, however investigators quickly saw through her lies.

On Wednesday, the seven-member board did not accept her requests for 'mercy',  even as she attempted to squeeze out tears. 

Mr Smith was also unmoved by her assurances that she had changed since the horrific killings. 

David Smith, whose two sons were murdered by their mother, his ex-wife, said he felt 'much relief' after learning her request for parole had been denied

David Smith, whose two sons were murdered by their mother, his ex-wife, said he felt 'much relief' after learning her request for parole had been denied

Susan Smith, who murdered her two children, 'pretended' to cry during her parole hearing before her request for freedom was denied

'Susan hasn't been remorseful in my eyes,' Mr Smith said. 'Not one bit since she's done this, not one bit have I seen any remorse from her, so I wasn't expecting anything from her.'

Smith's chances of freedom were slim. Data shows the board grants approximately 8 percent of parole requests for violent offenders.

However, Mr Smith revealed he was still 'worried' she could be released and had been talking to his sons to help prepare for the hearing.

'I talked to Michael and Alex a lot beforehand,' he said. 'We had a lot, we had a lot of discussions beforehand.'

His wife of 30 years Tiffany, who also appeared in the interview, explained how the whole family, including the couple's 23-year-old daughter Savannah, had been forced to reckon with the terrible crime.

'When the life sentence was given, it was like, you know, it's going to 30 years is going to be a long time down the road. That's going to be long time away,' she said. 

'So, for, you know, for 30 years, you know, we haven't had to think about Susan all these years.

'And then the last six months, as her parole has come up, it's like, you know, she is, she has been at the front and foremost every day trying to deal with this and, you know, not wanting her to get out because it to us, it would not be justice for Michael and Alex.'

Mr Smith explained how the pain of his loss has barely subsided since the 1994 murders

Mr Smith explained how the pain of his loss has barely subsided since the 1994 murders

Smith, 53, drowned sons Michael, three, and Alex, 14-months, in a South Carolina lake in 1994

Smith, 53, drowned sons Michael, three, and Alex, 14-months, in a South Carolina lake in 1994

Mr Smith spoke at his ex-wife's parole hearing to campaign against her release

Mr Smith spoke at his ex-wife's parole hearing to campaign against her release

Mr Smith explained that the loss his sons still looms large in his life, despite the passage of time. 

 'Maybe it does heal some, some wounds, but for me, personally, time does not heal. The losing of a child, that one it does not heal,' he said.

'It used to be for me, on anniversaries or holidays or just landmark dates, it was really tough.

'But then it, then it got to where it could, it could be the eighth year, the 12th year, just a random year that got really tough to deal with. So, it's, it's up and down all the time.'

He admitted that over the years he has thought about 'what they would look like, or what they would be like have chosen as a career'.

But in my mind, I always come back to three and 14-month-old,' Mr Smith said.

At the time, prosecutors claimed that Smith was having an affair and had murdered her children in order to be with a man who did not want kids.

Smith was sentenced to life in prison with possibility of parole after 30 years

Smith was sentenced to life in prison with possibility of parole after 30 years

However, investigators soon picked holes in her story and uncovered the grisly truth.

However, investigators soon picked holes in her story and uncovered the grisly truth.

 At her parole hearing, the killer's lawyer argued that the murderers were a 'mental health story' and argued that she had changed. 

But Mr Smith pointed out that her sentence served was just '15 years per child'.

The boys' half sister Savannah Smith also spoke before the board and urged them to keep Smith behind bars.

'Growing up, I didn't quite understand it my whole life, but when I finally did, I felt like I had witnessed it, like I was there,' Savannah said.

'The pain that not only was caused to me and I in like a domino effect. But what I've seen firsthand with my father, my aunt, and our whole hometown, we can no longer say that we're from Union County without Susan's actions being brought up.'

Smith will be eligible to apply for parole again in two years, but the family say they are prepared.

'We are united,' Mr Smith said. 'We're going to be there every two years.'