HONG KONG - More graphic details on the gruesome killing of a 12-year-old girl, allegedly by her own mother, has emerged from the police investigation, Hong Kong media said on Tuesday (Dec 19).

He Meijie, a mainland Chinese student living and studying in Hong Kong, was chopped up into dozens of pieces and had had her face ripped off, the Chinese-language Ming Pao reported, citing sources.

It added that police had notified the girl's father, who is divorced from her mother and lives in China, to come to Hong Kong to collect her remains.

The girl's dismembered body was discovered on Sunday (Dec 17) night when police visited the subdivided flat in Mong Kok district she and her mother lived in for an unrelated complaint. A neighbour had made a police report after the 37-year-old mother, identified only by her surname Cao, refused to return a cellphone she had borrowed.

Police removed 12 bags of body parts from the 60 sq ft (5.54 sq m) flat. Some of the organs were believed to have been flushed down the toilet by Cao, who was arrested on suspicion of murdering and dismembering her daughter.

She was suspected to have been taking drugs and used a chopper on her daughter's body after becoming delirious, media reports said on Tuesday.

The woman, who has gone through two failed marriages, works as a masseuse in a night club to support her daughter and herself, Apple Daily reported on Tuesday (Dec 19).

It is believed that Cao was in the habit of taking methamphetamine, and police had found a flask for consuming drugs, as well as condoms at the crime scene.

Police have not been able to record a statement from Cao as she has been in a state of confusion since her arrest, sources told Apple Daily.

Mong Kok assistant district commander Chung Chi Ming said of the crime scene on Sunday: "Her head, organs and body had been mutilated. The shower was blocked, which resulted in flooding that affected neighbouring flats."

Cao had borrowed a mobile phone from her neighbour at around 7pm on Sunday, claiming that her cell phone was being tapped and that she needed to make a phone call to her husband to seek help. The neighbour called police when Cao failed to return the phone despite repeated reminders.

Police arrived at the scene at around 9pm on Sunday. They had to break down the door as Cao refused to let them enter the flat, reported South China Morning Post.

On Monday, forensic pathologists took away other items, including blood-stained jewellery and laundry detergent.

A neighbour who lives opposite the flat said on Monday that she heard chopping noises, which lasted about half an hour, coming from the flat at around 3pm on Sunday. Following that, there was a strong smell of disinfectant, the neighbour said.

At around 7pm on Sunday, she saw water flowing out of Cao's unit and down the staircase, the neighbour added.

Cao and her daughter came to Hong Kong more than three years ago after she married a Hong Kong man, Apple Daily said.