A child killer who murdered a seven-year-old girl in 1992 has been jailed for at least 29 years.
David Boyd, 55, lured Nikki Allan to a derelict building in Sunderland where he beat her and stabbed her 37 times.
Judge Mrs Justice Lambert said Nikki must have endured “unimaginable fear” in the moments before her death.
Boyd, who was eventually snared by DNA advances in 2017, was sentenced to life after being convicted of murder earlier this month at Newcastle Crown Court.
Nikki “knew and trusted” Boyd but he “took advantage of her young age and naivety” when he “tricked” her into following him on the evening of 7 October 1992, the court heard.
She was last seen skipping to keep up with Boyd, who was a neighbour and her babysitter’s boyfriend, as he walked towards the Old Exchange building.
Boyd had a “sinister purpose” when he lured Nikki to wasteland outside the abandoned building and her “fate was sealed” when she screamed and Boyd decided to “kill her to silence her”.
He struck Nikki in the face “to shut her up” then pushed her into the “pitch black building” where she “must have been petrified”.
“She must have quickly known she was trapped,” Mrs Justice Lambert said.
Nikki was attacked and killed in another room suggesting she had tried to flee her attacker.
“Her fear, as she saw you lurching towards her in the dark, is unimaginable,” Boyd was told.
“It must have been a truly terrifying experience for this seven-year-old girl.”
Boyd hit Nikki on the head with a brick, fracturing her skull, and then repeatedly stabbed in her in the chest before dragging her down a flight of stairs and dumping her body in the basement.
The judge said Nikki’s murder had “shocked and bewildered” the community of Hendon, in the east end of Sunderland, for 31 years and as time passed Boyd would have “thought with some relief” that he had “got away with it”.
However, the science of DNA had also advanced in the decades since the murder, which allowed detectives to match samples from Nikki’s clothes to her killer.
Mrs Justice Lambert said under current rules she would have jailed Boyd for a minimum of 37 years but she had to comply with the sentencing regulations in 1992 which suggested a lesser sentence, albeit one “well in excess of 20 years”.
Speaking after sentencing, Nikki’s mother Sharon Henderson, 57, said she was “absolutely devastated” by the sentence which she labelled a “disgrace”, adding Boyd should have been jailed for life without the possibility of parole.
“This is what happens to families like mine over and over again – injustice,” she added.
In an earlier statement read to the court, Ms Henderson recalled her daughter as a “bright and sparky child” who had a “beautiful smile and was loved”.
The story of Sharon Henderson and her hunt for her daughter’s killer.
She was 25 when Nikki was murdered and was “accused of being a bad mother” with “local people angry towards me and not towards the person responsible”.
She said Boyd “destroyed” her family’s lives but she had “fought tirelessly and endlessly” for justice.
Ms Henderson said she had suffered mentally and physically and “at times targeted those who I believed were covering for others” which led to her own arrest.
She said: “I felt so frustrated over the years, as I felt I had not been listened to.”
Nikki’s father, David Allan, said he was 28 when Nikki was murdered and “from that night my life changed”.
In a statement, he said he felt “anger and hatred” towards the killer and would “never be able to forgive the man responsible”.
Mr Allan said the “devastation” he felt was “indescribable” because Boyd had “lived his life for 30 years whilst Nikki did not get to live hers”.
Northumbria Police initially charged another of Nikki’s neighbours, George Heron, with her murder but a judge presiding over the then 24-year-old’s trial in Leeds in 1993 said the detectives’ questioning had been “oppressive” and he was cleared.
After the case, he said: “Finding out about the current investigation has been difficult – so many details and negative memories; bringing up mixed emotions about what happened back in 1992 and since.
“I feel sadness, disgust, anger, betrayal by people I expected to tell the truth (especially the original investigating officers).”
Following Boyd’s conviction, the force apologised to Mr Heron and to Ms Henderson, although she rejected their words as “hollow”.
She has called for a public inquiry into the force’s “historic failures” in her daughter’s case, and has been backed by the legal charity Centre for Women’s Justice.
Prosecutor Richard Wright KC said the 1992 investigation was “utterly misconceived” and made multiple errors, but the team who re-opened “the troubled and challenging” case started from scratch with “no assumptions”.
Police collected DNA samples from more than 800 men from around the country, took 1,200 statements and produced 2,500 documents.
The judge commended the “Herculean” effort and said the DNA evidence gathered had been “critical” in convicting Boyd.
The court had heard Boyd was a neighbour of Nikki’s in the Wear Garth flats, he knew how to navigate the Old Exchange building and had sexual fantasies about young girls.
He also had 22 convictions for 45 offences including sexual crimes.
In 1986, he exposed himself to a woman. He later told a psychiatrist he had been doing it since the age of 16 and “couldn’t control” the urge.
That same year he was convicted of breaching the peace in Sacriston, County Durham, when he grabbed a 10-year-old girl in a park and tried to kiss her.
In 1997, he admitted to police he exposed himself to three teenage girls but was not charged.
Two years later he groped a nine-year-old girl in a park in Stockton and confessed to a probation officer that he had “dirty thoughts” and “sexual fantasies” about young girls.
In mitigation, Jason Pitter KC, for the defence, said Boyd had a history of mental illness, learning difficulties and an IQ level “in the bottom 2% of the population”.
However, the judge dismissed that as irrelevant because he used “sufficient guile” to lure Nikki away from her home and was quick to cover his tracks by conjuring a false alibi.
She said there was no guarantee Boyd would be released from prison and it would be up to the parole board to decide.