Sarah Payne's siblings describe guilt after her murder and not being able to save her

The three siblings of murdered schoolgirl Sarah Payne have spoken publicly for the first time about the moment she disappeared and the feelings of guilt they have battled at not being able to save her.

The eight-year-old had been playing a game of chase with her brothers Lee and Luke and younger sister Charlotte in a cornfield in 2000 when she ran ahead of her siblings.

Lee Payne, who was 13 at the time, told a Channel 5 documentary he was "literally 30 seconds, if that, behind her," as he chased after her in the area near their grandparents' home in West Sussex.

He said when he couldn't see Sarah he thought she was hiding because "she’d left in a huff" after falling over.

Sarah had dipped through a gap leading to a road on the edge of the field in the village of Kingston Gorse, where she was snatched by paedophile Roy Whiting, who bundled her into the back of his van.

Lee, now 30, recalled what would become a brief, chilling encounter seconds later.

"As I was walking up the road Whiting drove the other way in his van," he said. "(He) gave me a little wave as he went."

Sarah's body was found two weeks later. Whiting was convicted of her murder a year later.

Luke Payne, who was then 12, said the thought he too could have somehow prevented his sister's death "eats you up inside".

He said he is still haunted by what happened 17 years on.

"I don’t get a lot of sleep," he said. "I dread the night, because it’s just you and your thoughts."

Luke, now 28, said he always wonders "where (Sarah) would be at, what she would be doing" as he sees her friends now getting married and starting young families of their own.

Sarah's killing led to a new law on child sex offenders - known as Sarah's Law - being passed in 2011 after a campaign led by her mother Sara.

The Child Sex Offender Disclosure Scheme allows anyone to ask police if someone with access to a child has a record for child sex offences.

Luke said his memories of Sarah are much more than the little girl the public knows through the law and her sweet school photograph.

"The thing is they don't actually know how special she really was," he said.

"They just see a picture and a face and just a name to a law. But that makes her special to everybody else.

"In reality she's so much more, or was so much more - or could have been so much more..."

Charlotte Payne though said she believes her sister "was put on this Earth" to help her mother create Sarah’s Law.

While being only five at the time, Charlotte said she too has felt guilt about her sister's death, asking: "Why was it her and why not me?"

She added: "When something bad like that has happened to someone you love you almost feel guilty for even being alive and you're not."

Charlotte said she suffers from anxiety and until turning 18 was "too scared to even go out of the house sometimes".

Lee said he had often questioned his own role in the events of 1 July 2000 throughout his teenage years.

He said: "I did for a few years beat myself up about it, thinking that if I had maybe ran faster ... I might have caught up with her ... thinking that if I had had me head on that day realised that she was in the back of that van.

"But ultimately I was a 13-year-old kid, there's not much you're able to do."

He said coming to terms with Sarah's death is still something that happens "day-by-day" and he accepts may never end.

"There's never going to be a day when you’re going to turn round and be like, 'I’m over that now', because it’s just not going to happen,” he said.

Sarah's mother Sara Payne, who is the focus of the documentary, also said her mental anguish over her daughter's killer changed during the trial.

"When I saw him in the court for the first time, I realised, that he really wasn’t a monster," she said.

“It was then that I realised, he’s just a sad, lonely person that actually goes after children because he couldn’t have a relationship with an adult.

"What I realised was, in the whole of the court case, was he did not care about me, Sarah, the children - it was just a means to an end, it was never, ever about us.

"It was never, never about her, it was just about what he wanted."

Sarah Payne: A Mother's Story airs on Channel 5 on Wednesday at 9pm.