Nikki Allen disappeared from her home in Sunderland, Tyne and Wear, on Wednesday night after being out of her mother's sight for less than a minute.
Her body was discovered by a neighbour yesterday morning. Police said she had been clubbed to death with a blunt instrument.
A post-mortem examination showed she died of multiple head injuries. She was so badly beaten that her killer fractured her skull. There was no sign of a sexual attack. Police believe she was killed in the basement of the warehouse.
Nikki vanished after leaving her grandparents' flat in Wear Garth, Sunderland, to go to her mother's ground-floor home in the same block. Her mother, Sharon Allen, sent her ahead to watch television. She looked over the balcony and saw her daughter alone, three doors from home. By the time she went downstairs Nikki had gone.
A relative alerted police after a family search failed to find the girl. A police helicopter, sniffer dogs and 30 officers joined in the search and detectives found her purple jacket and shoes by the river Wear. Her body was found in the warehouse, which used to be a recording studio.
Police suspect that the killer lives locally and may have blood- stained clothing as a result.
Detective Superintendent George Sinclair, who is leading the murder inquiry, said: 'This was a particularly brutal and vicious attack on a very small and fragile child. She was savagely beaten about the head and she put up no defence . . . Whoever did this wouldn't need to be a very big person, Nikki was small for her age and very frail.'
Mrs Allen, who is separated from Nikki's father, David, was last night under sedation. She has three other daughters.Reuse content