Son of killer Rowan Baxter who murdered estranged wife Hannah, three children suing her parents

The son of killer dad Rowan Baxter, who set his estranged wife Hannah Clarke and three children alight in a horrific murder-suicide, is suing her parents for a share of their daughter's $3.6 million estate.

The 31-year-old and her children, Laianah, four, Aaliyah, six and Trey, three, were killed by Baxter, 42, when he doused the family's car in petrol and set it alight in Camp Hill, Brisbane, on February 19.

The children died in the vehicle while Clarke succumbed to her burns in Royal Brisbane Hospital later that day. Baxter died by suicide at the scene.

His son Isaiah Jesse Rowan Baxter has since filed a case in the Brisbane Supreme Court against Lloyd and Suzanne Clarke for part of their daughter's assets.

"My relationship with Rowan was strained for my whole life as a result of his abusive and controlling behaviour towards me... and towards my mother and Hannah," he said in his affidavit, according to The Courier-Mail.

He said the deaths of his father, step-mother, and half-siblings were "incredibly traumatising" and he believes he will "continue to suffer" for the rest of his life. He filed the lawsuit to help with "building my future" and "moving on with my life as best I can".

According to court documents, Baxter filed the claim within days of learning his father's $1.8 million life insurance would go to Hannah's estate, not him.

"I believe that they both would have intended to provide for me financially in the event of their deaths," he said.

He believes the Clarkes received $1.8 million in life insurance for Hannah and another $1.8 million for Baxter since the policy stipulated the payment must go to her, even after she dies. He also said her parents got $1.5 million raised through a GoFundMe campaign, which was set up to cover funeral and living costs.

"To the best of my knowledge Hannah's parents are the beneficiaries of her intestacy... To the best of my knowledge they also own their own home and are financially sound," he said.

Baxter is currently unemployed and is unable to receive a benefit in Australia since he was born in New Zealand and doesn't have a driver's licence.

He is currently living with his mother and father in North Lakes, north of Brisbane.

The Clarkes told The Guardian in a recent podcast that Baxter would rape their daughter daily and say "awful" things in her ear, make her steal clothes from shops, and told her she looked "terrible".

They said Hannah and Rowan, who is a New Zealander, met in 2008 when she was 19 and he was a 30-year-old father.

After the pair married in 2012, Baxter's behaviour changed so much it was like "flicking a switch".

"As he got a grip over Hannah, he removed her from her brother and from us - he started putting in wedges, and it wasn't until then that we realised how controlling he was," Hannah's father Lloyd Clarke said.

Hannah and the three children fled to her parents' home in Camp Hill Brisbane in late 2019 after realising they were in danger.

Where to find help and support: