A Perth man accused of murdering his six-month-old baby told detectives he shook the child and threw her on the ground because he was "frustrated" by her crying and "just wanted her to shut up".

Key points: Six-month-old Isabella Martin was found with catastrophic brain injuries in her cot

Six-month-old Isabella Martin was found with catastrophic brain injuries in her cot Arron Martin shook her and threw her to the ground, the court heard

Arron Martin shook her and threw her to the ground, the court heard His lawyer said Mr Martin adored his daughter but he had "just snapped"

Arron Colin Martin, 37, made the comments during a video interview with police recorded in the hours after he walked into the Armadale police station on November 9, 2017, and said he had hurt his child Isabella.

Mr Martin is now on trial accused of murdering the baby, who the Supreme Court heard suffered catastrophic brain injuries.

The Director of Public Prosecutions, Amanda Forrester SC, said the child may have survived for between two and five hours after being injured, but Mr Martin did not seek any help for her.

The court heard Mr Martin worked overnight as a baker at a supermarket, while his wife Nicole worked during the day as a manager at a fast food outlet.

Isabella suffered catastrophic brain injuries, the court was told. ( Supplied: gofundme )

In the police interview played to the court on Monday, Mr Martin described how in the three months leading up to the incident he would come home from work about 10:00am and his wife would walk out the door to go to her job while he looked after Isabella.

He said on the day of her death, he had tried to put Isabella to bed about 4:00pm so he could go to sleep, but "she just wouldn't stop crying".

"The crying got louder and louder and louder," he said.

"I got up three or four times to put the dummy in her mouth but it didn't work. That's when I picked her up and just shook her.

"She wouldn't stop so all of a sudden I just threw her on the floor."

One of the detectives then asked Mr Martin how tall he was, and he replied, "six foot, it's a long way down".

'I just regret what I've done'

Fighting back tears, Mr Martin said he picked up the child and noticed that her eyes were slightly open and she had "a slightly husky breath coming through".

"I just put her back in the cot hoping that she would wake up," he said.

"I stayed in the room just patting her."

Isabella was injured at her Brookdale home and later pronounced dead in hospital. ( ABC News: Graeme Powell )

He said after about five minutes he walked out because he "couldn't cope any more", he tried to cut his wrist and then hang himself, but the electrical cable he used snapped.

He said he then went to a park to cool down before going to the Armadale police station.

Under further questioning he said he was not thinking at the time he shook and threw the baby, telling the detectives "it was probably a build-up of stress … I just work … everything is crap".

"I just wanted her to shut up," he added.

At the end of the interview he was asked if there was anything else he wanted to add and he broke down crying and said, "I just regret what I've done".

Accused 'just snapped', defence lawyer says

Mr Martin's lawyer John Rando described his client as "a family man who loved his wife and loved and adored his daughter".

He said his client faced "the dilemma" of having to look after his baby during the day when he was hoping he could recover and get some sleep.

"He was doing the best he could, but something happened on that day … he just snapped," Mr Rando told the court.

"He shook the child and she ended up on the floor and died. He was shocked … he was so traumatised he tried to kill himself."

Mr Rando maintained Mr Martin, who also suffered from anxiety, had not intended to do any harm to his child.

No indication anything was wrong: mother

Giving evidence to the trial, Isabella's mother Nicole Martin described her daughter as "really good".

"She would put herself to sleep but sometimes she'd cry for half an hour," she said.

Nicole Martin said she found out what had happened to Isabella after returning from work. ( ABC News: Joanna Menagh )

Ms Martin said the last time she saw her child, who was recovering from a cold at the time, was before she went to work, when the baby was in her bouncer.

She said her husband had just come home from work himself and she was running late, so they only spent about 10 minutes together before she left.

Ms Martin told the court she then received text messages from him during the day asking about her getting a day off, and he gave no indication at any stage that anything was wrong.

She said she eventually found out what happened to her daughter when she arrived home that evening to find police and ambulance officers at the house.

Under questioning from Ms Forrester, Ms Martin said she and her husband did not have any help from anyone else to look after Isabella, because their families did not live nearby and they were trying to save money.

The trial is expected to run for one week.