The woman so obsessed with serial killers she became one & how her writing revealed telltale signs of what was to come

FROM a young age Jemma Lilley immersed herself in horror – shelves of gory films, blocks of razor-sharp knives in her home, and a dark obsession she could barely hide: the fantasy of killing someone.

And on June 13 2016, that fixation turned real.

For years, the British expat, who grew up in Stamford, Lincolnshire, fed the obsession as she talked about murder, wrote about it and imagined it – and before long the urge inside her was “getting stronger and stronger.”

Lilley herself had a deadline in mind – she wanted to take a life before she turned 25.

In November 2017, Jemma Victoria Lilley, 26, and Trudi Lenon, 43, were found guilty of murdering 18-year-old Aaron Pajich-Sweetman – who his mother described as a “precious little boy.”

But Lilley’s fascination with violence didn’t begin there.

After moving to Australia from the UK when she was 16, The West Australian journalist Tim Clarke told Mama Mia’s True Crime Conversations podcast: “She got a job. She made some friends here, but her whole persona, even from a young age, appeared to revolve around horror.

“She once said in some of her writings that the character Freddy Krueger from the Nightmare on Elm Street movies, was her father figure.”

As her interests in horror, torture and weapons intensified, the idea of killing consumed her imagination.

She started writing her own novels and even penned a graphic story called Playzone, which focused on a murderer known only as SOS, who tortured victims for pleasure.

When she became angry, Lilley would warn people: “SOS. is coming out.”

But according to Tim, her obsession with the character soon spilled over into real life.

He explained: “She had several tattoos depicting this SOS character on her body. Even the motorbike that she rode in in Western Australia in Perth, the registration number was one SOS one.

“As she grew out of her teens and into her early 20s, she saw herself as this SOS character – and this SOS character was a serial killer who would torture and murder victims himself.

“But then more centrally to the story that emerges in real life, he had followers that would also do his bidding, do his killing for him.”

Jemma’s father, Richard Lilley, supported his daughter’s writing but admitted the material unsettled him because it was “a little bit too graphic.”

Others were more blunt.

“A lot of people thought she had a mental problem,” he said, speaking to Sunday Night.

Speaking to The Times after the conviction, Lilley’s stepmother, Nina Lilley, said: “The book was a big problem with me. At the beginning I was, ‘fair enough you want to write a horror story’, but I didn’t like the contents of it.

“She had always had an obsession with serial killers but she said it was a way of venting her frustration of what happened when she was a child.”

As a young woman, Lilley became a regular at a local video shop, where horror films filled her evenings.

The shop’s manager, Angela McKibbin, would later recall how the once quiet customer began sharing something far more disturbing than movie recommendations – the violent fantasies that seemed to consume her.

“She liked horror movies and that’s the only genre she would rent,” she said, speaking to Sunday Night.  

“She told me that she wanted to kill someone and that the feeling that she had was getting stronger and stronger.

“She didn’t know if she could control it for much longer. And that she wanted to kill someone before she was 25.”

Lilley eventually found someone willing to help turn fantasy into reality – her accomplice, Trudi Lenon.

The mother-of-three, who was in her mid-40s and shared a home with the 24-year-old in Perth, became Lilley’s “best friend, her muse, her confidant, and ultimately became her accomplice,” Tim Clarke explained, speaking on the True Crime Conversations podcast.

Lenon had been involved in the BDSM scene in Perth for some years, and became a “submissive” to Lilley.

He went on to say how he believes that Lilley felt that she couldn’t do it alone, adding: “If you jump back to one of the central themes of her book, it was that she needed someone.

“SOS had these followers, these sickopaths that would do his bidding and killing for him and honoured and worshipped him.

“And in Trudy Lennon, that’s what Gemma found.”

Lenon introduced Lilley to 18-year-old Aaron Pajich-Sweetman, a friend of her son who lived on the same street and had known the family for years.

Months before the killing, the pair exchanged messages that would later shock investigators. In June 2016, Lilley texted Lenon describing a violent craving she said she could not shake.

“I feel as though I cannot rest until the blood or flesh of a screaming victim is gushing out and pooling on the floor, until all the roads and streets are stained red,” she wrote.

Lenon replied: “It is definitely time – I am ready, you are ready.”

The pair also visited hardware stores on three occasions, purchasing items including a circular saw, bleach, acetone, cement, a drop sheet, a large plastic barrel and 100 litres of hydrochloric acid.

Inside their home, they prepared a “torture room,” complete with a gurney, blue tarpaulins lining the walls, and an array of weapons including a bone saw, a machete and dozens of knives.

On June 13 2016, the two carried out the killing after luring Aaron to the house after making him think he was coming to fix a computer.

Pajich-Sweetman, who had Asperger’s syndrome, trusted Lenon because of his friendship with her son.

Police said she lured the teenager to a nearby shopping centre before bringing him back to the house she shared with Lilley.

As reported by the ABC, it was Lilley who eventually led police in her direction after she bragged about the murder to a colleague five days after, telling them she “wanted to become a serial killer, and she wanted to leave her mark.”

A week later, his body was discovered buried in a shallow grave beneath a concrete slab in the back garden. He had suffered multiple stab wounds, had been garrotted and had cling film wrapped around his face.

When officers searched the home, they also found a large saucepan containing mouldy meat, which police suspected had been used in an experiment involving hydrochloric acid.

Police uncovered a trail of incriminating evidence at the scene, including blood and DNA inside the home, CCTV footage showing the victim entering the house with both women, and disturbing messages between the pair detailing their desire and plans to kill.

Despite this, Jemma’s father Richard still defended his daughter.

When he asked his daughter whether she had killed the teenager, he told Seven’s Sunday Night programme: “She said, ‘No, 100 per cent I did not’. And with the emotion in her eyes I believe her.

“I know my Jemma. She hasn’t got a bad bone in her body.

“I said, ‘Whatever happened we’ll get through this and if you’ve played any part bring it out now and deal with it’. And she swore to me that she did not play any part and there was never any — she said you will not find any evidence against me. No DNA.”

Once in custody, both defendants blamed each other for the killing.

Lenon told the court Lilley approached the teenager from behind as he installed games on her computer, garroted him until the wire broke then stabbed him three times.

The prosecution said Lilley left incriminating messages to her “obsequious and sycophantic” follower Lenon hours after the killing, saying she was feeling things she had “not felt before.”

During a four-week trial, prosecutor James McTaggart told the court Lilley wanted to kill someone before she turned 25, and once she had ticked off murder from her “bucket list” she was so “full of herself and euphoric” that she could not help boasting to a work colleague.

In February 2018, both women were sentenced to life in prison for murder.

Delivering the sentence, Justice Stephen Hall said the killing had been driven by their shared fascination with violence.

“The idea of killing another person was something that excited both of you,” he told the court. “You killed for your own pleasure.”

“She had always had an obsession with serial killers but she said it was a way of venting her frustration of what happened when she was a child.”

Following the verdict, the victim’s emotional mother Sharon Pajich told reporters she was heartbroken and would have to deal with what happened to her son for a lifetime.

His murderers were “disgusting animals” and should never be released, she said.

“He was my precious little boy, he was my first-born … he was full of life.

“They (the killers) deserve everything they get for what they’ve done, they’ve taken an innocent boy from his loved ones.”