POLICE arrested Sunderland man Steven Grieveson, 43, early yesterday morning on suspicion of Nikki’s murder.
He spent the day being questioned by detectives leading the investigation at a police station in Tyneside.
The arrest follows a resurgence of activity in the case.
It was triggered by a television reconstruction documenting the last minutes of the eight-year-old’s life, filmed to mark the 21st anniversary of her death.
Following the screening of the BBC programme, Northumbria Police detectives revealed they were investigating a series of new leads.
Filmed in the city, officers were hoping the programme would provide that vital piece of evidence.
Nikki vanished after leaving her grandparents’ flat in Wear Garth, East End, on October 7, 1992.
Her battered body was found the following day in a derelict building, lying in a pool of blood. She had been stabbed 37 times in the chest.
Nikki’s mum, Sharon, was interviewed for the reconstruction at Gill Bridge police station and relived that harrowing night all over again.
She said: “It might have been more than 21 years ago, but it still feels like yesterday.
“The pain never goes away, the anger never goes away.”
After the programme aired, Detective Superintendent Roger Ford, from Northumbria force’s Major Crime Team, said his team were looking at a number of new leads.
Det Supt Ford added that detectives had been particularly keen to hear from a woman who called and claimed to have information she withheld from the original investigation.
At the time, officers described the new information as positive and “very significant”.
Since then, Sharon has been updated on the police investigation and was confident progress was being made.
The East End community where the family lived also rallied behind Sharon, coming forward with their memories of the night.
A rally was held in the area just a few days after the programme, while a giant “Justice for Nikki Allan” sign was painted on the gable end of a building in High Street East.
Police today renewed their appeal for information.
A spokesman for Northumbria Police said: “The investigation into Nikki’s death has been ongoing for the last 21 years and officers are making a fresh appeal for anyone with any information to come forward.
“We are particularly keen to speak to anyone who lived in the Wear Garth area at the time of the killing or anyone who hung around or inside the Old Exchange Building.”
* Anyone who thinks they have information that could help detectives with inquiries is asked to contact police on 101 ext 69191.