A young mother who initially denied killing her four-month-old daughter in May 2017 has changed her plea and confessed to her murder.
Cassandra Doohan was charged with her baby Anastasia Hand's death after the infant was found unresponsive by her father in her cot at the couple's Capel home.
Prosecutors alleged the baby suffered a "catastrophic brain injury" and died in Princess Margaret Hospital four days later.
In the Supreme Court of Western Australia last year it was revealed the cause of the baby's death was not in dispute, but who was responsible for the death was.
Police prosecutors said the baby had suffered a catastrophic brain injury and a post mortem found bleeding to the brain and suggestions of abuse.
It was alleged the little girl woke up about 6.30am in the communal bedroom on May 24 and her father, David Hand, 21, went to change her nappy and give her a bottle.
He then went on to get showered and dressed while the baby was cooing in her cot.
After he was finished getting dressed the mother asked him to bring the baby over to her bed so she could say good morning to her.
Mr Hand went to pick the baby up from her cot and found her unresponsive.
Trial dates for the matter have been vacated, with Doohan expected to be sentenced on September 9.
Her defence lawyer has requested extensive psychiatric and psychological reports in order to argue against a life sentence being imposed.
An adult found guilty of murder must be sentenced to a minimum of 15 years life imprisonment, unless it would be unjust in the circumstances to do so.