LURID Facebook messages between two women accused of killing a teen and burying his body under concrete in a Perth backyard have emerged in court.
The extraordinary exchanges between Jemma Victoria Lilley, 26, and Trudi Clare Lenon, 43, reveal how their bizarre relationship intensified in the lead up to the murder of Aaron Pajich, 18.
Prosecutors say Ms Lilley and Ms Lenon lured Mr Pajich, who had Asperger syndrome, to their Orelia home in June last year before stabbing him to death.
They allegedly buried him in their backyard, covering the shallow grave with concrete and red tiles.
On Wednesday, the jury at WA's Supreme Court watched a recording of Ms Lenon's being grilled by detectives about messages she and Ms Lilley allegedly sent each other between March and May last year.
Their friendship, which had begun just weeks earlier, was developing into one close enough to be planning a murder, the court heard.
In the series of messages published by Perth Now, Ms Lilley allegedly adopted a persona called "SOS", which was the name of a serial killer character she had written in a book.
In reply, Ms Lenon allegedly used the persona of "Corvina", a name she had used years earlier when she was involved in the bondage and sadomasochism scene.
In one message said to be written from Ms Lenon to Ms Lilley in March last year, she tells her: "For me, the chance to see SOS in hunt mode excites and scares me. I so want to meet SOS, but I know that will be pushing new territory for both of us."
And in another, Ms Lenon allegedly tells her younger friend: "I feel so much more alive, my mind is opening up … I am becoming aware of my own darkness.
"Even now, just writing this is highly erotic … I truly want to serve you."
When asked about the messages, Ms Lenon told police she believed they were merely writings "fleshing out our characters" for future books the pair were planning to write alongside each other.
But detectives investigating Mr Pajich's murder repeatedly put to Ms Lenon they were in fact evidence of them planning a murder.
"I didn't plan any of it," Ms Lenon said. "I didn't bring him there for her to kill."
In further messages, Ms Lenon is allegedly referred to as a "good servant" and an "accommodating servant" by Ms Lilley, who also says she is proud of her.
The pair are said to have discussed their "history in the making" and leaving behind a "legacy".
And then in the final message extracted by police, Ms Lilley is alleged to have written: "I feel as though I cannot rest until the blood or flesh of a screaming victim is gushing out and pooling on the floor … I cannot shift this belief that the world has become not only ready for me but it needs me to be ready."
Prosecutors allege Ms Lenon replied: "It is definitely time - I am ready, you are ready."
This exchange is said to have taken place 13 days before Mr Pajich was garrotted and then stabbed to death in the Orelia home the two women shared.
His body was later discovered buried under a DIY patio allegedly constructed by the pair in the week after his killing.
Both women deny the murder, although Ms Lenon has admitted to being an accessory to murder.
The trial continues.