25 years on, James Bulger's mother relives the day her boy was taken by two 10-yo killers.

Just after 3.30pm on Friday, 12 February 1993, the hand of two-year-old James Bulger slipped from his mother’s.

The pair were in a butchery at the New Strand shopping centre in Bootle in the UK. James’ mum, Denise Fergus, had let go of her son’s hand only to pay the butcher for two pork chops.

She grabbed the package and looked down to find James – her “beautiful” James who was “real and fizzing with life” – had disappeared. “Getting my purse out to buy two pork chops for tea was the last thing I did before my world imploded forever,” she wrote in a book extract published in the The Mail on Sunday.

It’s a crime that’s evoked horror and disbelief in people – especially parents – in the 25 years since that moment when James left the safety of his mother’s side and was led from the shopping centre clutching the hands of his two 10-year-old murderers.

In her new book, I Let Him Go, Denise said she felt relief, initially, when she was shown that now-famous CCTV footage of the two boys leading her son out of the shopping mall. She thought the three of them must be playing house somewhere. No one could imagine 10-year-olds to be capable of such evil.

"Immediately everyone went from fearing the worst to discussing the fact that they could be mucking around with him in a garage, feeding him Mars Bars and treating him like a kid brother," she wrote on Saturday.

"I was sure I would get James back. How could two young lads possibly want to harm my child when they were just children themselves?"

Now, she knows that relief was unfounded. It was a moment of hope that came crashing down when James' tortured body was found two days later on a railway track, and she realised the harm those two "lads" had inflicted.

"Not James. Not my beautiful boy. This couldn’t be happening to me, I didn’t ever let him out of my sight," she wrote.

Denise replays her movements on the day of James' abduction over and over in her head relentlessly. A slow-motion clip in which the horrific outcome can never be undone.

"What I will remember until my dying day is walking over to James’s pushchair [before leaving for the mall], putting my hand around the right handle ready to collapse it to put it in [the car], and thinking to myself: 'No need to bother with that, Denise – we will only be nipping in and out. You can just hold his hand'."

She hasn't slept soundly since her little boy was killed and says her her heartbreak is made even more desperate by the fact she lost a daughter to stillbirth the year before James was born.

"I remember thinking on that day in hospital: ‘Today is the worst day of your whole life, Denise. It will never get worse than this'," she wrote.

"But two years later, leaving The Strand shopping centre without my little boy’s hand in mine, well that was the worst thing of all. Then I became a mother of two children, but without either of them by my side."

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James' body was discovered two days after his abduction, on February 14, in Walton - less than 5km from the shopping centre and fewer than 100m from the police station.

Police, now hunting for the toddler's murderers, were given a lead when a woman recognised one of the figures in the slightly enhanced CCTV footage playing on the news, TruTV reports.

She called police and led them to 10-year-old Jon Venables, who she knew was absent from school that Friday, which then led to his accomplice, 10-year-old Robert Thompson.

The two boys, who were just 10 years old at the time of the killing, were jailed for life but released on licence with new identities in 2001. Earlier this week, Venables was charged over indecent images of children for a second time, AAP reports.

Writing in the Mail, Denise said: "People often ask me if I blame myself for what happened that day - for taking my eyes off him for that split second; for letting go of his hand as I looked for my purse; for not seeing what the CCTV footage later showed: Jon Venables and Robert Thompson beckoning James away from my side and out of the shop at 3:39pm."

"The answer is: of course I do. There aren't the words to describe how I still feel now, every day. I was the one who let go of his hand; I was the one there meant to protect him."

She goes on to share her "biggest regret" is that she didn't turn right instead of left upon leaving the butcher.

"If I had taken the right turn and gone around the corner, I would have seen James being led away, just four short minutes after he had left my side, trustingly holding hands with the boys who were about to murder him.

"I just felt like I had let James down and, in all honesty, if I couldn’t have him back then all I wanted was to be curled up in that casket with him."

Denise Fergus has penned a book, titled I Let Him Go. It will be released on January 25 with a portion of proceeds to be donated to the James Bulger Memorial Trust, which supports families of victims of crime. To buy the book, click here.