A teenage girl who killed her 18-month-old niece 'to get the evil out of her' was locked up indefinitely in a mental hospital today.

Julia Nguyen, 19, of Talbot House, in Hornsey Road, Holloway, admitted manslaughter.

The court heard she had smothered Mya Nguyen while babysitting at her brother's home in Vale Terrace, Harringay.

When the parents returned to the house she refused to hand over the child, who appeared pale and lifeless.

Nguyen told them Mya was evil and “she had been getting the evil out of her”.

The teenager later told police: "You don't understand. It is in the hands of God now. I removed the spirit. I'm the only one who can undo what I did to Mya."

Nguyen was charged with murder but pleaded guilty to manslaughter on the grounds of diminished responsibility after being diagnosed with schizo-affective disorder.

Judge Richard Hone ordered her to be detained indefinitely under the Mental Health Act.

He said: “The death of Mya is a family tragedy and one in which you deeply share. You exhibited florid symptoms of schizo-affective disorder at the time. However there is no sign of any assault or any restraint."

The judge said he was influenced by a statement from Mya's parents Jimmy and Annie, which described Julia as “a vulnerable young woman who is clearly troubled and in need of medical attention and not imprisonment”.

Their statement continued: “Julia will live with the guilt for the rest of her life and incarcerating her serves no meaningful purpose.”

Nguyen is of Vietnamese origin but was brought up and educated in the UK.

Her parents and brother said her behaviour changed after she moved out to live with friends.

When she returned to the family home in Holloway she dressed differently and started referring to God.

Prosecutor Brian Altman said: “Her mother heard her listening to religious music. She would dance and then laugh like the devil and make references to witchcraft.”

On August 17 last year she was babysitting Mya at her brother's home. Neighbours saw her cradling the baby in her arms and playing loud religious music on her phone.

When Julia's father and mother returned to the house later that afternoon they saw her lying down holding Mya.

The teenager then took the child into a bedroom for an hour until the rest of the family arrived.

When they went into the bedroom they saw Julia touching the baby's eyelids and saying: “Let Julia save Mya”.

Paramedics managed to restart Mya's heart but the girl's condition deteriorated and she was pronounced dead three days later.

Mr Altman said that experts could not identify the cause of Mya's death but added it was consistent with smothering, although it was not possible to diagnose this.