Stuart Hazell has admitted murdering his 12-year-old step-granddaughter Tia Sharp after dramatically changing his plea to guilty during his Old Bailey trial.
The 37-year-old had maintained that Tia had fallen down stairs and her death was an accident at their home near Croydon, south London.
He had previously denied murder and sexual assault.
Tia was reported missing on 3 August and was last seen at the house of Hazell's partner Christine Sharp, Tia's grandmother, in New Addington.
Her body was found wrapped in bin bags in the loft of her grandmother's house a week later.
This morning the jury was brought back in and the charge was formally re-read to the defendant.
He bowed his head, shuffled his feet and then pleaded guilty, prompting sobs and gasps from the public gallery.
UPDATE: Hazell has been jailed for line with a minimum of 38 years.