Lance Lachlan Murdoch was at primary school when his heroin-addicted father killed himself, was 12 when he began using drugs and 15 when he first appeared in court.
His crimes culminated in 2013 when the now 30-year-old shot dead a Sydney shop worker during the last of a spate of armed robberies.
Murdoch faced a sentence hearing in the NSW Supreme Court on Wednesday, after being found guilty last year of murdering Villawood Value Fruit Market worker Kamran Yousaf on October 12, 2013.
An associate who wielded a hammer during the robbery has already been jailed for the murder.
Murdoch has failed drug jail tests and says he has no desire to undertake professional intervention to address his drug use, his lawyer William Brewer told Acting Justice Jane Mathews.
"He needs a breakthrough somehow," Mr Brewer said while referring to Murdoch's prospects of rehabilitation.
Murdoch had spent more than half of the time since he was 15 in custody and, despite court orders, has resisted any treatment for drug and alcohol abuse.
"It seems to me Mr Murdoch needs some counselling to motivate him to want to go beyond relapsing into drugs," he said.
His father committed suicide when Murdoch was at primary school, he was kicked out of school in year eight, has very poor literacy skills and cognitive development, and suffered serious injuries in a motorcycle accident.
Murdoch is also facing sentencing in other courts for armed robberies and a firearm offence.
The judge said she hoped to sentence him for the murder before September 30.
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