Hazell, 37, was jailed for life with a minimum of 38 years yesterday. He changed his plea to guilty on the fifth day of his trial at the Old Bailey on Monday, 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 Tia was killed in an accident when she fell down the stairs, but the court heard that the window cleaner sexually assaulted her before murdering her and hiding her body in the loft of the home he shared with her grandmother Christine Bicknell.
Natalie Sharp, the mother Tia Sharp outside the Old Bailey in London on the day that Stuart Hazell, the man accused of Tia's murder changed his plea to guilty
Hazell had lived with Ms Bicknell in New Addington, south London, for more than five years before Tia died, and developed a twisted sexual attraction for the schoolgirl who often stayed with them, and secretly filmed her while she was asleep.
Natalie Sharp, who briefly dated the convicted drug dealer before he began a relationship with her mother, told ITV's Daybreak she would have one question for Hazell if she visited him: "Just - 'why?'. But then, is he going to answer the questions? Then I want to put my hands around his throat."
Ms Sharp said justice "will never be done" for Tia and that she wants Hazell to be "beaten, brought back and beaten again".
Hazell murdered Tia when the pair were left alone on August 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 apologised.
Ms Sharp said Hazell had been trusted "100%" with her children and that she had not known of his violent streak.
"He was like two different people," she told Daybreak. "The person I thought we knew was soft and gentle and friendly, there wasn't an inch of bad bone in him."
She added that Hazell changed his plea "five days too late" and that the trial meant the family had not yet had time to grieve.
In an interview to be broadcast by ITV tomorrow night, Ms Sharp spoke of the graphic evidence the family had to sit through.
"All he had to do was (plead) guilty in the first place and no one would have known any of this bad stuff that she had to go through," she said.
"She could have rested in peace on her own without all of this. And I hate him even more for this."
The judge, Mr Justice Nicol, said it was most likely that Tia was smothered, and it was clear that Hazell had developed a sexual interest in her.
After finding the body, police discovered he had a fascination with child pornography, and had searched for obscene material online using terms including "violent forced rape", "little girls in glasses" and "incest".
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.
As he sentenced Hazell yesterday, the judge said of Tia: "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 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.
"The tragedy of their loss and her death is because of your act in murdering Tia Sharp. You are responsible."
Tia was described by her mother on Daybreak as "lively, bubbly, happy" and a "typical 12-year-old" with "more front than Brighton". Ms Sharp said she was not a bad mother, adding: "She was loved. She never went without."
Ms Bicknell, also interviewed for the documentary, said she thought the schoolgirl was safe being left with her partner, but now realises "she'd have been safer on the streets with a stranger".
She said she had no clue that Hazell was harbouring sick thoughts about her granddaughter.
"He treated me like a queen," she told the documentary. "I lived with a man that I loved with all my heart, that was my world.
"There's nothing that I should have picked up on. He remained the same as always."
Living With A Killer will air on ITV tomorrow at 7.30pm.