The man who set fire to a car containing his wife and children had a childhood filled with abuse and pornography, according to a relative.
At just 14 years old, Alana Hampson ran away from the home she was living in with Rowan Baxter and his parents.
Despite having nowhere else to go, the teenager didn't like the environment and the situation scared her.
Now 38, she is speaking out about the vile personality traits she saw existed in her first cousin as they grew up together and the uncomfortableness she felt living in his home.
Former NZ Warriors league squad member Baxter burnt his family alive in their car earlier this month after a custody battle with his wife Hannah.
Laianah, four, Aaliyah, six, and Trey, three, died at the scene while Hannah Clarke succumbed to horrific burns in hospital later that day.
Baxter stabbed himself to death at the scene.
Alana Hampson believes it was in childhood where the mindset was created capable of dousing his three children and ex-wife in petrol before igniting a flame that ended their lives.
Hampson claims the family, who she is now estranged from, has "dark secrets" that gave the murderous "monster" the tools to grow into a man with an ability to end his children's lives with a single flame.
Friends who knew Clarke have since come forward depicting turbulent times the mother-of-three faced during the couple's relationship and in the aftermath of their separation last year.
Her best friend Lou Farmer said she had been aware of his possessive behaviour towards Clarke for quite some time and an aggressive manner in which he would speak to her.
Hampson believes that attitude was in ingrained in him from a young age.
"He was very controlling and manipulative," she said.
Controlling and manipulative
"I think that Rowan should have been going through counselling as a kid. The kids got into porn, always looking at porn, his mum accepted it, he treated his mum like crap, she was a nice lady."
When Hampson's mother called to tell her what Baxter had done, she says she was shocked but not surprised.
"I couldn't swallow it at first, but when I did swallow it, all these flashbacks popped up in my mind."
When Baxter was in his twenties, his mum died suddenly of a brain aneurysm - an event she believes sent her cousin further down a path of destruction.
As a result of her troubled past, Hampson says she deals with mental health issues but the hurt has been on herself.
"People can change because I had the most ugliest life, he did too, but I changed. You still have those demons but it's how you cope with them."
In a heartbreaking confession, Baxter's son from a previous relationship, Isaiah, who had been estranged from his father for several years, said he could relate to Clarke.
'We shared a similar bond, as we both suffered years of domestic abuse and torment at the hands of Rowan,' Isaiah wrote in a heartbreaking message to her family.
"His appalling parenting caused irreversible damage to my mental health. If I could take the place of Laianah, Aaliyah, and Trey I would in a heartbeat."
Hampson recalls his cruel ways as a victim of abuse himself, recalling that he was into porn and sexually active from a young age.
"He was a monster, even when he was a kid, I think he was a monster," she said.
She says she feels extreme pain for Baxter's three children and Clarke, devastated the pain in his life caused harm to so many more.