The judge described them as a group of "immoral assistants" brought together to carry out one man's "awful plan".
That plan was the murder of solicitor Katie Foreman, 31, whose bedroom was doused in petrol and then set alight as she slept in the early hours of October 27, 2011.
On Monday, the man behind the plot, Bradley Max Rawlinson, and two of his "associates" were sentenced to a combined total of 59 years in jail.
The court heard that Rawlinson, Ms Foreman and another woman, Wendy Evans, were part of a love triangle and that, through lies and manipulation, the 42-year-old man convinced Evans to murder Ms Foreman.
Rawlinson lied to Evans, telling her that Ms Foreman had threatened to kill a member of his family and "end me". He said the only way for them to be together was for the solicitor to be killed.
On one occasion, Rawlinson texted Ms Foreman, writing "good night beautiful, I love you", only to tell Evans soon after "I want her gone because I want to spend the rest of my life with you".
Believing Rawlinson's lies, Evans plotted the murder, bringing in Michelle Sharon Proud, a distant associate whose only interest in the crime was money, which she accessed via a TAB account.
Proud, in turn, brought in a fourth man who cannot be named for legal reasons.
On the night of the murder, Evans and the unnamed man went to Ms Foreman's home with a bucket of petrol, creeping in using a key provided by Rawlinson, and doused the young woman's bedroom with petrol while she lay sleeping.
"It is difficult to contemplate ... a more excruciating or frightening way to die," Justice Ian Harrison said. "I'm satisfied that [Evans'] participation came about, to a considerable degree, under the influence of Mr Rawlinson and the web of lies and deceit he had spun.
"He manipulated her emotionally and psychologically, painting the deceased as an immovable object to them growing old together."
After the murder, Rawlinson turned on Evans, telling police that it was she who had been manipulating him and had threatened to kill the member of his family.
These claims, Justice Harrison said, were so unbelievable they "bordered on the bizarre".
"He demonstrated a cold indifference to the deceased's right to live in her own way and on her own terms," he said.
A psychologist's report tendered during the sentencing noted that Evans may have been particularly vulnerable to Rawlinson's charms because of the depression she was suffering from, her addiction to painkillers and her upbringing.
After the murders, Evans told a mental heath professional that she hated herself for what she had done and now realised things she believed about the deceased were not true. The 41-year-old said she "may have been searching for a father figure".
Rawlinson was sentenced to a maximum of 36 years in jail with a non-parole period of 27 years. Evans was sentenced to a maximum of 24 years with a minimum of 18.
Proud was sentenced to 20 years' jail, with a non-parole period of 14 years, for her role in the murder.
"She was a willing and enthusiastic contributor in the plan to cause very substantial harm to the deceased," Justice Harrison told the court.
Justice Harrison said he accepted Proud had not known of any intention to kill Ms Foreman, referring to her "naivety and ignorance".
The judge also took into account Proud's special circumstances, including a major depressive illness and her precarious financial situation.
