It looked just like her baby. And yet the mother became convinced her daughter had been replaced.
The six-week-old child in her arms was not her own but "something else". Beset by a rare mental disorder known as Capgras delusion, the mother took a long knife from the kitchen last July.
The 26-year-old had arrived from Senegal the year before with her elder daughter, joining her husband in Wallsend, Newcastle after years spent apart.
The mother – who cannot be named for legal reasons – suffered no mental illness during pregnancy or in the weeks after the birth, a court found in a September hearing.
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The father noticed nothing wrong until two days before the killing when his wife told him she was unhappy in her heart but did not want to see a doctor.
The father sought out anti-depressants the next day, gave her some and found her much happier. That evening, she discussed the baby's upcoming naming ceremony on the phone with friends, who also found her "very happy."
But the next day, after reporting feeling ill, she slit the child's throat. The father came home to find his wife and the baby lying on a blood-soaked mattress.
The mother was still there when police arrived.
"Get up, you're under arrest for murdering your baby," a senior constable said, twice, but she did not respond.
Charged with murder, she pleaded not guilty, her lawyers arguing a defence of mental illness.
The mother had told forensic psychiatrist Richard Furst that in the weeks after the birth she became anxious and depressed.
"Weird voices" called her and she came to believe her child was "not my baby, something else I was holding and had to deal with," she said.
"It was quite scary. More like a devil thing I was holding."
For Dr Furst, this suggested a Capgras delusion, in which the look of a familiar person is not matched by the brain's usual emotional response.
Sufferers are not hallucinating - their visual perception remains undistorted - but they come to believe the person they know has been replaced by an identical-looking impostor.
An online search of NSW case archives reveals only a handful of other instances.
In one, a woman thought an impostor had received plastic surgery so as to appear as her mother, whom she stabbed to death. In another, a mother killed her son thinking his soul had been sucked out to leave a "changeling" behind.
Dr Furst found the Newcastle mother depressed and psychotic at the time she killed her baby. When interviewed by another psychiatrist in May, she remained concerned her baby had been replaced by something resembling a devil.
Supreme Court Justice Robert Allan Hulme found the mother not guilty of murder and sentenced her in September to confinement in a mental facility, where she remains.
According to the Black Dog Institute, one to two women in every thousand will suffer from psychosis after pregnancy. That amounts to between 300 and 600 women each year.
Perinatal Anxiety and Depression (PANDA) national helpline 1300 726 306