The 37-year-old changed his plea on the fifth day of his trial at the Old Bailey, having forced 12-year-old Tia’s family to sit through days of shocking and graphic evidence, including a sickening picture of her taken after she died.
He had claimed that Tia was killed in an accident when she fell down the stairs, but prosecutors said that the window cleaner sexually assaulted her before murdering her and hiding her body in the loft of the home that he shared with her grandmother Christine Bicknell.
Tia’s grandmother could be seen crying and hugging a relative.
Mr Justice Nicol said: “She was a sparky girl who was full of life but you took that life from her. All that lay ahead of her — a career, loves and a family of her own — will now never be. And the loss of her has been devastating for her mother, her father and all her relatives and friends.
Hazell, a convicted drug dealer, had lived with Ms Bicknell in New Addington, south London, for more than five years before Tia died.
The window cleaner, who had previously briefly dated Tia’s mother Natalie Sharp, developed a twisted sexual attraction for the schoolgirl, secretly filming her while she was asleep and putting cream on her legs.
Hazell murdered Tia when the pair were left alone on Aug 2 last year at the New Addington house while Ms Bicknell worked a night shift.
Her blood was found on a sex toy in the house and on his belt, and his semen was on the bed clothes in the bedroom where she slept.
After he murdered the 12-year-old, Hazell wrapped her body in a sheet and layers of plastic and hid it in the loft.
It was not found until a week after Tia died due to two failed police searches of the loft, for which Scotland Yard has since apologised.
Some of Tia’s relatives shouted “Nowhere near long enough” and “RIP Tia” as they walked past journalists outside court.
The judge said it was most likely that Tia was smothered, and it was clear that Hazell had developed a sexual interest in her.
However, the judge said he could not be sure that Tia’s murder was sexually motivated, which would have meant a whole life jail term, and that it could not be proved to the criminal standard that the photograph was taken of Tia after she died.