Cassandra Rose Doohan was aged 18 when she violently shook four-month-old Anastasia (pictured), inflicting catastrophic injuries on the infant, at their Capel home in Western Australia's South West region in May 2017.
Anastasia's father found her limp and "floppy" body in her cot after he came out of the shower and the girl died at Princess Margaret Hospital in Perth two days later.
The Supreme Court was told the baby died of head and neck injuries, but a post mortem examination revealed Anastasia had numerous other injuries including broken bones that were likely to have been inflicted in the days and weeks before the fatal assault.
Doohan, pleaded guilty to her murder, with the Supreme Court hearing she also admitted mistreating the baby in the weeks before.
The court was told Doohan's relatives had regularly seen injuries on the baby, including bruises on her face, a friction burn to her neck and a blood clot over her eye.
The baby was taken to hospital about two weeks before her death, but Doohan explained away the injuries as being a result of Anastasia scratching herself and rolling around her cot.
Someone anonymously tipped off child protection authorities and they visited Doohan and her partner before setting up a safety plan for the family.
But five days before the fatal assault Doohan's brother witnessed her holding Anastasia out in front of her and under the baby's arms, violently shaking her until she stopped crying.
OnSeptember 9, 2019 in the Supreme Court of Western Australia Justice Anthony Derrick ruled the crime was so serious that only a life sentence was appropriate, and ordered that Doohan serve at least 13 years behind bars before she can be released.