A week from giving birth to her first child, the sister of murdered Dawesville teenager Jessie Cate has broken her silence over the senseless tragedy, describing her ex-boyfriend as a "compulsive liar" who she never thought would be a violent killer.
Emma Cate has given an insight into the mind of Kyle Rohan Garth, 20, saying his behaviour towards the end of their four-month relationship in July last year became increasingly strange.
Garth was jailed for life this week in the Supreme Court, with a minimum of 18 years, after admitting to the strangling murder of the popular and bright 15-year-old.
Miss Cate met Garth when working at Woolworths in Falcon.
She said that when he broke up with her, he was "bawling" on her kitchen floor saying his father had died. She found later that was a lie.
She said Garth had also lied about his childhood, claiming he had lived with his father overseas.
The 18-year-old said the break-up was amicable and her family had nothing to do with Garth for five months before he killed Jessie.
"He came across as a nice guy, a gentleman almost, then when I started unravelling all his lies I started second-guessing him," she said.
Miss Cate said despite his web of lies, she never thought Garth was capable of violence.
Garth had offered Jessie a lift home from her after-school job at Woolworths, in Falcon, on December 12 last year. After about a minute in the car, he started choking her. After he realised Jessie was still alive, Garth strangled her with one hand as he drove for 10km, then buried her in a shallow grave.
Miss Cate and her mother said they believed Garth sought Jessie out for some premeditated reason.
They reject his explanations - that Jessie was unhappy about his relationship and his absence as a role model to her younger siblings.
"You don't know what to believe because he's made up so many different stories and none of them seem reasonable," she said.
Judy Cate said she believed Garth's life was unravelling, but his motive remained a mystery.
"I don't think we'll ever get the answers we need. Deep down he knows the truth," she said.
Ms Cate said Garth's actions - including phoning her with a concocted story and playing video games with a friend after the murder - were the actions of a "natural born killer".