Perth thrill killer's appeal dismissed after just a minute

Perth thrill killer Jemma Lilley has lost her final fight for freedom, with the WA Court of Appeal dismissing her case.

Lilley murdered autistic teenager Aaron Pajich to live out a violent fantasy in June 2016.

It took less than a minute for the court to dismiss Lilley's appeal much to the relief of the family of her teenage victim who were sitting in the public gallery.

It brings to an end a three-year legal process.

Jemma Lilley and her partner Trudi Lenon were 27 and 45 when they lured 19-year-old Aaron Pajich to their home in Orelia in Perth's south.

They strangled and stabbed him to death before they buried his body in a shallow grave in the back yard, laying concrete and tiles to cover their tracks.

Both were handed life sentences but Jemma Lilley appealed on a number of grounds.

She tried to argue a book she authored as a 16-year-old shouldn't have been used as evidence against her.

Titled 'Playzone', the book is a fantasy story of a fictional male serial killer.

The court said Lilley wanted to emulate the character in her book and that 'Playzone' was evidence of (Lilley's) character and of a tendency that she had an obsession in serial killers and murder generally.

Lilley also tried to argue her collection of knives should not have been used against her.

Police found machetes, scalpels and butchers' knives at her house.

The court found the collection of knifes was relevant because it showed Lilley was "more likely than an ordinary person to use a knife to stab someone". Lilley and Lennon will serve life sentences with a 28-year minimum.

Aaron's father and stepmother say they will now try to move forward.

His mother, Sharon Pajich was flanked by family outside court and spoke briefly to media. "We are just going to move forward now and move on," she said.