The mother of a slain Toowoomba teenager has rounded on the turncoat friend who helped plan her son's grisly stabbing murder but was too squeamish to witness it.
Joanne Lasker and her husband John on Tuesday pledged to keep their son Jake's memory alive after Kyle Dumesny pleaded guilty to manslaughter and was jailed for seven years.
The 19-year-old's brutal 2012 death at the hands of Dumesny and another young friend, Max Peter Smith, was planned in a macabre series of text messages.
The pair discussed how they might kill Mr Lasker after Smith described him as "not useful to society".
Dumesny appeared to go along with the plan by responses such as "lol" and "cool".
"The conduct went on for several days," Supreme Court Justice Peter Lyons said in sentencing Dumesny in Toowoomba.
"It plainly reflected an intention that some harm be inflicted upon Mr Lasker."
Smith struck when the three had started playing Xbox in Mr Lasker's room in November 2012, stabbing Mr Lasker 102 times with a carving knife from the kitchen amid cries of "please stop". He is currently serving a life sentence.
Crown Prosecutor Vicki Loury said Dumesny, who was "squeamish" about blood, was in the toilet at the time of the prolonged attack and then fled from the home.
Mrs Lasker, in her victim impact statement, said Dumesny could have stopped the murder.
"Even though you didn't kill him, you still helped plan it," she said.
Dumesny, now 21, was charged with murder but pleaded guilty to the lesser charge of manslaughter on Monday, when his trial was meant to begin.
Ms Loury said Dumesny gave varying accounts to police that he either thought the texts were a joke, or was too scared to say anything.
Defence barrister Stephen Kissick stressed his client's young age and said he had no appreciation of Smith's intent to kill.
Dumesny, who has been in protective custody since May 2015, was having a tough time behind bars because other inmates believed he was willing to give evidence against Smith, Mr Kissick said.
Mr Lasker, who had Asperger's Syndrome, had survived a cancer scare months before his death.
Outside court, Mr Lasker said the crime was senseless.
"Keep his memory alive, there's not much more we can do than that," he said.
Mrs Lasker said the "horrific ordeal" had ruined lives across three families.
"If you don't like someone, don't take their life," she said.
"It's not worth it. Just walk away. That's all they had to do."
Dumesny will be eligible for parole in October 2017.