Inside the shocking downfall of AFL star Shannon Cox who started smoking meth at 13 - before killing two women in horror car crash when he was coming down from the drug

The awful meth-fuelled downfall of Collingwood star Shannon Cox has been laid bare in court as he was jailed after killing two women in a car crash with his 12-year-old daughter in the vehicle.

Cox was sentenced to 10 years and six months' imprisonment on Wednesday, and will be eligible for parole after serving eight years and six months, backdated to October 25, 2024.

The father of two girls will also be disqualified from driving for four years after he is released.

Cox admitted to unlawfully killing Thelma Clausen and Coral Seinor after he fell asleep at the wheel and crossed into the path of oncoming traffic about 170km north of Perth just before 9am on June 7, 2024.

The 39-year-old, who played 25 AFL games for Collingwood between 2007 and 2009, had taken meth two days before and was found to have 0.77 milligrams per litre of methamphetamine in his system when he was treated in hospital after the crash, the Western Australian Supreme Court heard.

Cox's experience with the drug started in his childhood.

The court heard he started using methylamphetamine when he was just 13 years old, with his lawyer Paul Holmes stating Cox had been 'bagging up drugs before he was taught how to ride a bike'.

Holmes told the court his client also started drinking alcohol at around that time after he was exposed to violence in the early part of his childhood.

Cox – who didn't learn to read until he was an adult – moved to Melbourne when he was 20 and used alcohol to cope with stress and his gambling habit.

Footy provided discipline for the former defender after he was picked up by Collingwood in the 2006 AFL rookie draft and got promoted to the club's senior list after starring for Williamstown in the VFL, making his first-grade debut in 2007.

The forward joined the mining industry after he retired in 2009, citing a lack of passion for the game.

Cox started using a significant amount of methamphetamine in 2015 and served two years and six months in jail for drug-related offences, Justice Stephen Lemonis said as he passed sentence.

About 18 months before the accident that killed Ms Clausen and Ms Seinor, Cox's methamphetamine use escalated significantly, and he was on a community-based order for drug-related charges at the time of the accident.

His arrest over the women's deaths was the third time in two years he had been caught driving with methamphetamine in his system, and while on bail for the manslaughter charges, he was again caught using the drug.

'This offending has tragically come about because of your addiction to methamphetamine,' Justice Lemonis said.

Thelma Clausen's daughter Leanne spoke of her frustration at how Cox had breached his bail conditions by going on to take drugs again following the crash.

'How could someone take drugs and destroy two innocent lives and then show no remorse?'

Suzanne Seinor said her mother Coral 'lived for those she loved and loved unconditionally'.

'You chose to drive a car with drugs in your system,' she said, addressing Cox during her victim impact statement.

'That choice resulted in taking two lives that weren't yours to take.

'Your choice affected over 1,000 people, who were my mum and her friend's family, loved ones and community.'

Ms Seinor added: 'To you, she was just some old lady. To me, she was my mum, my friend, my confidant.'

Cox was travelling from Geraldton to Perth with his 12-year-old daughter, Josephine, who was also injured, to pick up his wife after she was released from custody when the incident happened.

After the victim impact statements were read, Holmes requested that the hearing be adjourned after his client became emotional.

He added that Cox was 'truly remorseful'.