The mother of murdered schoolgirl Nikki Allan made it a personal mission to hunt down her daughter's killer for over 30 years.

Disillusioned by decades of police blunders and inaction, Sharon Henderson, 55, took it on herself to track down David Boyd.

In the end Boyd was brought to justice by a combination of her refusal to let the case be forgotten and diligent police work by a cold case team which was only appointed because of her persistence.

In 2016 Sharon had a meeting with Northumbria Police's Chief Constable Steve Ashman and begged him to make sure the case was reopened by a new team before his retirement as top cop.

As the cold case team harnessed new advances in DNA technology, Sharon continued her own enquiries.

The Northern Echo: Killer David Boyd Killer David Boyd (Image: Contributor)

She gradually got closer to Boyd's ex girlfriend Caroline Branton and her daughter, Caroline junior.

She even moved across Sunderland from her native Hendon to within a few doors of the Brantons in the former pit village of Ryhope.

Sharon learnt of Boyd's true identity at around the same time as Northumbria Police zoned in on him.

Boyd was tracked down to an upstairs flat in central Stockton-on-Tees.

He was DNA tested and found to be a one in 28,000 match for microscopic samples found at four sites on two items of Nikki's clothing.

The DNA was on the waistband of her cycling shorts and under the armpits of her T-shirt, which itself had been under her coat.

It would be the decisive factor in his trial.

Mrs Henderson said: "While there was still breath in my body I would never have stopped until the man who killed Nikki was found, nothing mattered more in my life than seeing justice for her.

"Over these thirty years I have been through hell. I've fought against problems with alcohol and I've been sectioned in a psychiatric hospital.

"But I knew I'd get him, one way or another, however long it took, I'd see him locked up.

"Sometimes it felt as though the police had forgotten all about the case and in truth, for long periods, they had.

"It felt like the only one who never forgot about Nikki was me and that was a lonely struggle."

The Northern Echo: Nikki Allan Nikki Allan (Image: Contributor)

Nikki was lured away by Boyd on 7 October 1992 as she played in the courtyard in the centre of the four sided, four storey square of flats.

The trauma of that night ruined Sharon's life but gave her a steely determination that Nikki's murder in the abandoned Exchange Building on the docks in Hendon, Sunderland, would not go unsolved.

Read more: Video shows moment Nikki Allan Sunderland murder accused is arrested

The Northern Echo: The Exchange Building in Sunderland The Exchange Building in Sunderland (Image: Contributor)
She began to try to track down any man who lived on the estate she had any suspicion about.

To help aid her memory she drew out a map of the block of maisonettes and tried to eliminate each in turn.

Eventually only one was left - David Boyd. At the time he was using the surname Smith and also Bell, so no one knew his true identity.

Sharon said: "Boyd arrived on Wear Garth because he was friends with my sister Sandra Prest's partner Terry Clarke.

"I've never been able to find out anything about his time before he moved to the garth in his early twenties.

"He moved to his girlfriend's flat in Wear Garth and lived three doors up from my Dad's flat, which was the last place we saw Nikki.

"He was a young man then, but a loner, the only time I can remember seeing him was when he was out on the veranda in front of the flats on his floor, I don't remember speaking to him.

"He was there during the police search for Nikki and always hanging around Terry and my sister's flat but after Nikki's death he left the garth.

"I couldn't get that thought out of my mind and I knew I had to somehow track down where he had gone.

"I made it my business to become friends with his girlfriend and her daughter and I even moved to Ryhope to be near them.

"I wanted to be close to them and find out what they knew about who and where he was. I just knew he had something to do with it."

Read more: Man accused of murdering Nikki Allan ‘admits fantasies of young girls'

The Northern Echo: Sharon at press conference on the 25th anniversary of Nikki's death Sharon at press conference on the 25th anniversary of Nikki's death (Image: North News)
The murder has taken its toll on Sharon's family ties and relationships.

She is now estranged from members of her family, including sister Sandra, the partner of Terry Clarke, who died in 2021.

Sharon said: "I've become estranged from most of my family through this, it's taken over my life.

"I spent many years drinking to dangerous levels because of this and since Nikki's death I've been admitted to psychiatric care.

"On the last occasion I went to hospital myself and told them I thought I was going to kill somebody if I wasn't admitted.

"My three other daughters have grown up knowing a mother who couldn't get over the death of their sister and who was drinking herself to death.

"They've lived with someone who just couldn't give up searching for the killer, my life has been on hold for 30 years until someone was finally brought to justice.

"But I know in my heart that some have got away with it and I'll never feel justice has been done entirely."

The last time she saw Nikki, earlier in the evening she was murdered, is burned into her mind.

Read next:

Nikki Allan murder trial jury hears of find of new DNA evidence

Nikki Allan: Jury in David Boyd murder trial told how body was found

Nikki Allan: Jurors see photos and sketches of suspect David Boyd

"I was doing some washing in the twin tub," she says. "I needed some pain killers and had run out so decided to go upstairs to my dad and step mam's flat.

"The youngest of my four girls were just babies then but Nikki and her older sister Stacey were still awake.

"Stacey was OK but Nikki insisted on coming upstairs with me. She was like that, loved to be around me and could be a little clingy, even at seven.

"So we went upstairs and I got my painkillers and was chatting to my step-mam. It was at that point my dad decided to get the hoover out and start cleaning the flat.

"Nikki hated the racket and said she wanted to go home. I told her to go on ahead, I'd be there in a minute. 

"I've played that moment over on my head a million times. It was the last time I saw her as she left through that front door."

Nikki's body was found later with 37 stab wounds and with injuries consistent with being hit by a brick.

There were no signs of sexual assault, the murder appeared to have been committed as an act of sadistic cruelty.

Subscribe to a Premium Plus package to The Northern Echo from as little as £1.50 per week and read more quality stories and extras. Click here

The Northern Echo: Nikki was a clingy little girl Nikki was a clingy little girl (Image: Contributor)

"She was a timid little thing," Sharon recalls. "She liked her dummy, even at seven, she took them from her sisters' cots.

"Sometimes I'd even sneak her one as she went to school and the teachers would ask later 'do you know where Nikki would have got a dummy from?'

"She loved to be with her mam and would run straight to me and into my arms when I picked her up from school.

"The thought of what that monster did to her in that building and the fear she must have felt will haunt me for the rest of my life and it has driven me on to get justice for all these years."