The disappearance of a little girl called Sarah Payne led to the "defining" campaign of Rebekah Brooks's editorship.
Speaking in her defence at the hacking trial, Brooks spoke at length about her personal involvement in the long-running campaign for Sarah's Law named after the tragic eight-year-old.
It all started just a couple of months after she became editor at the News of the World, she told the packed Old Bailey courtroom.
In July 2000, Sarah went missing during a family holiday at her grandparents in West Sussex.
Brooks said it was a "very big story" and she had a reporter on the scene, along with the rest of the national media.
Sarah's parents Mike and Sara had also stayed on to help in the search for their daughter.
Brooks said: "I asked if I could go and see Mike and Sara and see if there was anything we could do. I did not have any idea at the time formulated."
Brooks paid her visit just after Roy Whiting, who had yet to be caught for Sarah's killing, had been spoken to and released as part of the investigation.
Police picked him up because a check had revealed he had been convicted of trying to abduct another child and upon his release had gone to live near to Mr Payne's parents.
While she was waiting with a family liaison officer to speak to the Paynes, an officer commented to Brooks that they had a good idea who had taken her.
Brooks said: "I think before I went in to see Mike and Sara they said to me something like we think we know who it is because we've done a check and it sounds similar to Roy Whiting's MO (modus operandi)."
"I was really surprised and came back to do some research on it and it led me to Megan's Law which I think President Clinton introduced after a very similar situation in America…
"Megan's Law was introduced state by state..as a parent you would be able to go to the local police station and say 'is there anything we need to know….?'.
"That's how we came up with Sarah's Law."
She said she knew the campaign would be controversial – with concerns that unmasking paedophiles would lead to vigilantism – and said she did not tell Rupert Murdoch, nor Les Hinton, until very late.
She said they were "supportive of the campaign but critical of me not raising the flag earlier".
Brooks admitted that there were "some mistakes" during the News of the World’s campaign, such as including a picture of a teacher, who had been listed on the sex offender's register due to a relationship with a pupil, on the gallery of predatory paedophiles, prompting a "riot of sorts".
She said the newspaper set up a campaign centre, and had some two million badges.
Paying tribute to Sarah's mother Sara Payne, she said: "She found it a way to cope by being really involved. She was an amazing lady and she thought that this gave her an outlet."
Ten years on from the campaign start, the final piece of Sarah's Law went through, she said.
On the impact on her position at the News of the World, Brooks added: "It was a big thing. It sort of defined my editorship in a way."
All of the defendants deny all of the charges.
The trial continues.