A man who murdered his wife and three children by setting them on fire threatened a previous partner that he would kill himself and their child if she ever left him, a friend of the victim has said.
Hannah Clarke was emotionally, financially and sexually abused by her estranged husband Rowan Baxter for more than 10 years, friend Manja Whaley says.
The former domestic violence worker described Ms Clarke as the "most courageous woman I know" and said Baxter believed his wife had to be "punished" for leaving the relationship.
Ms Whaley posted a lengthy tribute to Ms Clarke on Facebook, in which she addressed her friend's battles.
"I asked you if he had ever threatened to kill you or the children and you told me he had not but there was one thing he had said, really matter of fact, when you first got together 10 years ago," she wrote.
Ms Whaley said Ms Clarke said her husband told her he had threatened a previous partner that if she were to leave him he would end his own life and that of their child.
Baxter killed Ms Clarke, Aaliyah, 6, Laianah, 4, and Trey, 3, when he doused them in petrol and set their car alight in a Brisbane street on Wednesday morning.
He died shortly after stabbing himself in the abdomen with a knife following the attack, police say.
Ms Clarke did not initially understand she was the victim of domestic violence, Ms Whaley wrote.
"At first you were confused and told me that you had never thought of being in a domestic violent relationship as you explained 'he never hit me'.
"This is not love. This is coercive control. The act of threats, intimidation, assault and humiliation or other abuse that is used to harm, punish his own children and wife."
Two days after they were killed, Queensland Police Commissioner Katarina Carroll confirmed police are treating their deaths as murder.
Ms Carroll said Detective Inspector Mark Thompson has voluntarily stood aside from the investigation over comments he made on Thursday.
Det Insp Thomson had said police were keeping an open mind about whether the deaths were a case of a "husband being driven too far by issues" or a woman and children suffering extreme domestic violence.
Ms Carroll will meet with Ms Clarke's family on Friday afternoon to apologise.
While setting out on the school run on Wednesday, Baxter approached their SUV and sat in the passenger seat.
Exactly what happened next is still being investigated, but a witness reported Ms Clarke jumped out of the car on fire in Raven Street, exclaiming "he's poured petrol on me".
The children, who were strapped into the back seat, perished in the flames. Ms Clarke, 31, died in hospital on Wednesday night.
Domestic violence campaigner Rosie Batty described the tragedy as "final act of power, control and ultimate revenge".
Baxter's online comments portraying him as a loving parent were "disturbing" according to Ms Batty, the former Australian of the Year whose son Luke was murdered by his father in 2014.
"A loving parent never considers murder as ever being an option or a solution. No one is ‘driven’ to murder no matter the circumstances or situation that they find themselves in," she said in a statement.
"Murder is a decision that is deliberate and driven by the need to exact revenge and achieve the ultimate act of power and control."
The confronting tragedy should also "give pause" to all politicians to think about their leadership on family violence.
"At least one woman each week is murdered," Ms Batty said.
The couple had been separated for months after Ms Clarke left the family home and took the children to her parent's house in nearby Camp Hill.
A Brisbane court granted at least one domestic violence order against Mr Baxter.
In text messages seen by 10 Daily, Ms Clark said she was glad she “took the big step”, in a message looking forward to 2020, saying it will be her “year”.
“Things are pretty bad,” the messages says.
“But I’m so glad I took the big step. I’m having good days and bad days but I’m sure that’s all part of it. I have all my babies back together and they can’t be taken again.”
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