A "prison confession" by Claire Tiltman killer Colin Ash-Smith provided a significant piece of new evidence that helped ensure his conviction.
Ash-Smith had evaded justice since 1993 for the brutal murder of the schoolgirl, but a change in the law and the testimony of a former prison inmate helped to finally see the case solved.
He confided details to Stefan Dubois, and the "confession" was used as evidence after cold-case detectives reopened the investigation and subsequently charged Ash-Smith with the alleyway murder.
Upon searching Ash-Smith's home last year, police found an edition of a local newspaper marking the first anniversary of Claire's death - kept as a trophy of the fatal attack.
Colin Ash-Smith, who was today convicted of the 1993 murder of Claire Tiltman, kept an "assault plan" in which he wrote of his "psycho state of mind" and detailed his various attacks and attempted attacks on local women.
In one entry in the diary he described a 1988 stabbing attack on a young mother - for which he was jailed - as his "masterpiece", dubbing it "95% successful".
However, he wrote that one abandoned attack at Swanscombe railway station in north Kent, was only "50% successful", adding: "I bottled it. Lucky for her I did, I suppose."
Another account described him breaking into the home of a woman he was stalking, cutting her clothes in a laundry basket before fleeing after hearing her husband in the sitting room.
In an unusual step only possible due to a change in the law in 2003, the diaries were used as evidence in his trial, and provided the backbone for the prosecution's ultimately successful case.
An "evil" former milkman convicted today of the 1993 murder of schoolgirl Claire Tiltman was first questioned in connection with the crime almost 20 years ago.
Colin Ash-Smith, now 46, was quizzed as a suspect by detectives in 1995 but was only charged earlier this year - prompting questions over how he evaded justice for so long.
He has been in prison since a year after, when he was convicted of stabbing two other young women that bore the same hallmarks as Tiltman's murder.
In one 1988 attack which he dubbed his "masterpiece", Ash-Smith had attempted to murder and sexually assault a young mother after pouncing on her, attempting to strangle her and then stabbing her late at night.
The young woman fortunately survived the attack.
Tiltman's parents both died before Ash-Smith could be brought to justice for their daughter's death, but other members of the family today said the verdict meant they could finally "rest in peace".
Lin and Cliff Tiltman spoke of their "complete shock" after their daughter's murder. They described their horror during a press conference. Both parents have since died.
Kevin Hand, who occasionally saw Colin Ash-Smith at the British Legion Club in Dartford and knew the Ash-Smith family, described him as 'creepy'.
During the trial the jury were shown ITV Meridian pictures of Colin Ash-Smith at Claire Tiltman's funeral.
The judge Mr Justice Sweeney warned Ash-Smith he faced a life sentence.
The only sentence I can impose upon a conviction for murder is one of life imprisonment. However it is also incumbent upon me to form a view as to the length of any minimum term.
This case has obviously been a very demanding case for any jury to have to sit upon. The crimes that you have had to consider are appalling.
I'm extremely grateful to you for the way in which you have gone about your duties with conspicuous responsibility and consideration from the first to the last.
Here is how events unfolded after the murder more than 20 years ago.Read the full story ›
Nigel Pilkington, head of the Complex Casework Unit for the Crown Prosecution Service South East, said Ash-Smith would have attacked many more women if he had the chance.
He is a man who is always looking, stalking - always looking to attack women. The fact he only attacks some of the time is because he is not going to attack if he is going to be seen.
He is thinking about it (attacking) all the time. How many times has he thought about doing it and then abandoned it? Probably hundreds of times.
I don't think he can help himself because he is in a 'psycho state of mind'. If you ask him if he wanted to kill Claire Tiltman, I think he couldn't stop himself.
Detectives branded Claire Tiltman's killer Colin Ash-Smith "pure evil" and said he should never be free to walk the streets again.
Detective Superintendent Rob Vinson, from the Kent and Essex Serious Crime Directorate Cold Case Team, said the murder was one of the most "horrific" and "emotive" cases he had worked on.
Ash-Smith is a very dangerous individual. He is a predator. He would be stalking women with evil intent (to carry out attacks) - some of which he carried out and some of which he didn't.
On the night in question Claire was in the wrong place at the wrong time
When you look at the writings and some of the things he has done, this is a very, very dangerous individual, and justice has been served at last for the brutal murder of Claire.