"For what it is worth, I cannot foresee your release," he said.
He said Chapman had carried out a "significant degree" of planning and pre-meditation in snaring Ashleigh.
Judge Fox added: "This was an evil scheme very carefully brought, and with considerable detail to trap your victim."
Ashleigh was suffocated and dumped in a farmer's field near Sedgefield after agreeing to meet Chapman.
In October last year, she was attracted by a picture of a young, bare-chested man that Chapman - calling himself Peter Cartwright - had posted on the website.
Later that month, she told her mother she was going to stay with a friend. Text messages showed she thought she was being picked up by "Peter Cartwright's" father.
Since the age of 15, Chapman had been the subject of several sexual assault investigations.
In 1996 he was jailed for seven years for raping two prostitutes at knifepoint.
Chapman had been known as a convicted sex offender in the Merseyside area since 2000.
A statement from Merseyside Police said there had been a nine-month gap between officers realising Chapman had fled his home there and the force issuing a nationwide wanted notice for him.
In September 2009 the notice was issued - a month before Ashleigh was murdered.
'Behind that photo'
Speaking outside court Andrea Hall, Ashleigh's mother, said the authorities should have done more to monitor Chapman's whereabouts after his release from prison.
She said: "Them sort of people shouldn't be allowed out into society anyway. I blame them (the authorities) for letting them out.
Ashleigh thought she was meeting another teenager
"He should not have been let out whatsoever and for the people that are supposed to keep an eye on them, they should keep an eye on these sort of people."
Mrs Hall warned parents to find out who their children were talking to on the internet.
She said: "Just put the message out that please, parents whose kids are on Facebook, please ask them to tell you who they're talking to. You just don't know who is behind that photo."
Facebook issued a statement after Chapman was sentenced saying it urged people not to meet anyone they had been contacted by online unless they knew who they were, "as there are unscrupulous people in the world with malevolent agendas".
It said there were a variety of measures people could use to protect themselves from unwanted contact and that Facebook strongly encouraged their use.
'Calculated and wicked'
Prosecutor Graham Reeds QC said: "Having invented 19-year-old Peter to make contact with girls, he now decided to invent Peter's dad in order to persuade Ashleigh that it was safe to get into his car.
"The plan he devised was calculated and wicked and it worked."
Mr Reeds said Chapman picked her up near her home, and then drove her to Thorpe Larches, near Sedgefield, where he attacked her.
He is a predatory sex offender who, through the tentacles of the internet, could reach out to the young
Det Insp Mick Callan, Durham Police
"After the rape, her arms were bound up again and further tape was put over her face, suffocating her to death," he said.
Her body was dumped in a gully up against a fence by Old Stockton Road.
Chapman was arrested the following day after a nationwide alert was issued to trace the car he had been using.
During initial interviews, he told police they could "crush his car" and made no mention of Ashleigh, but later he lost his nerve and told a stunned custody officer: "I killed someone last night."
He led them to the spot where her body was found, almost 24 hours after she left the family home.
Durham Police have admitted that, had he remained silent, the car would probably have been crushed and valuable evidence lost.
Det Insp Mick Callan, head of Durham Police's major crime team, said: "The truth is he is a predatory sex offender who, through the tentacles of the internet, could reach out to the young and the vulnerable.
"He knows full well that using his real name and picture would not grab the attention of any young woman for a moment.
"But by using the picture of a good-looking young man as a cover he has woven a web of attraction and deceit that has sadly had a murderous ending."
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