Ex-girlfriend of killer sports coach Paul Thijssen reveals terrifying ...

The startling insight comes as Lilie's heartbroken parents mark the one-year anniversary of their daughter's brutal death, by urging people to have tough conversations to stop the scourge of violence against women.

"It shouldn't happen and it just needs to stop," Lilie's father, Jamie James, told 60 Minutes.

Lilie James was found bludgeoned to death in the bathroom of a school gymnasium. (Nine)

Lilie and 24-year-old Paul Thijssen both worked as sports coaches at the private school, and had a brief five-week relationship before she called things off.

Just a few days later, after 7pm on Wednesday, October 25, 2023, Thijssen followed Lilie into the school gymnasium's female bathrooms and beat her to death with a hammer. 

Text messages a cruel hoax

Thijssen then used Lilie's phone to send text messages to her father, luring him to the school to find her.

Lilie’s parents are speaking out on violence against women on the anniversary of their daughter’s death. (Nine)

"[It] just shows the character that the person is … just an evil, evil monster," James said.

As Jamie went to the school to find Lilie, back at home Peta James was becoming more frantic, revealing she even tried calling and texting Thijssen, asking if he'd seen Lilie. 

"I tried ringing him and he wasn't picking up. Then I tried texting him, and when I read it back, I can hear the desperation in the text," Peta said.

Peta James sent a text message to Paul Thissjen on the night her daughter was found dead in a Sydney private school. (Nine)

Thijssen later drove across the city to Vaucluse in Sydney's Eastern Suburbs and dumped belongings in a bin, before phoning police and taking his own life. 

Back at the school, Jamie was still desperately searching for his daughter, when suddenly ambulances and police arrived, and everything changed. 

"You know it's not right, and then, yeah, [they] said it was her," Jamie said.

"I still can't believe that it's happened. She was just going to work." 

Jamie returned home in the early hours of the morning, alongside a detective, to tragically tell his wife and son that Lilie was gone. 

"I'll never forget it," Peta said.

"I'll never forget that one moment in time, [that] realisation that she'll never walk through that door again, will haunt me for the rest of my life."

Former girlfriend reveals terrifying encounter 

The rage displayed by Thijssen shocked many who knew him, who said there were no red flags to warn of his capacity for deadly violence.

But for the first time, one of Thijssen's former girlfriend's has revealed exclusively to 60 Minutes how she saw the monster behind the mask.

Paul Thijssen’s ex-girlfriend revealed her own terrifying encounter with the killer sports coach. (Nine)

The pair dated for several months and had what she described as a "pretty normal" relationship.

She recalled, though, he had "a lot of need for attention" and was always wanting her to share her location and to feature in her social media profile pictures.

Over the months she said Thijssen's obsession intensified and when she tried to break it off multiple times, he would beg her to come back.

"He'd asked to get back together and I'd said, 'No'," she said.

"And then he's very upset and he punched a tree. And I was like, 'Why did you just punch the tree?' Um, and he said, "Because I can't punch the one thing I want to'."

The woman recalls feeling "immediately fearful" and running back home, her fear growing when Thijssen was spotted outside her home at dawn two mornings in a row.

"I look up out of the kitchen window, and through the slats in our fence, I see Paul's face staring at me," she said.

"Then I scream and my dad comes running downstairs and grabs a cricket bat and he fully chases him down the street."

The woman said Thijssen looked "deranged" and as if "something was not right with him".

That frightening encounter was the last time she saw her ex-boyfriend.

A former girlfriend of sports coach Paul Thijssen, who savagely beat 21-year-old Lilie James to death in the St Andrew's Cathedral School gymnasium in Sydney, has revealed he reacted in a 'deranged' and violent manner when she broke up with him, years earlier. (Nine)

But incredibly, years later, as the police hunt for Lilie James' killer spread across Sydney, she instantly thought of Thijssen.

"As soon as I saw the headline, it didn't name who the person was, but I just knew it was Paul," she said.

She said it was "terrifying" to discover someone she thought she knew was capable of such violence. 

Paul was captured on CCTV footage the night Lilie James was killed. (Nine)

"Every time someone brings this up, I just think, 'That should have been me. It should not have been Lilie … it should have been me, if it was gonna be anyone'."

Remembering Lilie James 

There will be a coronial inquest held in March, seeking answers to Lilie's baffling and senseless killing.

As difficult as it is for her parents to talk about, they want to pay tribute to their beautiful and busy girl.

"She was hard working, she loved being involved," Peta said.

Lilie James’ friends hold on to memories of the vibrant high school sports coach. (Nine)

"She wanted to make people's days better, whether that was just with a smile or a quick conversation."

The couple also want to contribute to a bigger discussion, calling time on the domestic violence epidemic against women.

"We need to do more. We need to do more," Jamie said. 

"I think stop using [the] words 'It's complicated'. Let's uncomplicate it. It shouldn't happen, and to me, it just needs to stop."

Statement from St Andrew's Cathedral School head of school Dr Julie McGonigle

"We continue to stand with the James family in their grief. This one-year anniversary will be a challenging period for our community, especially as it falls during the HSC and IB examination period for many of those students most affected.

"We are focused on supporting our students, staff, and families now, and into the future and are very grateful to the broader community for the deep care the School has received."

1800RESPECT is Australia's national domestic, family and sexual violence counselling, information and support service call 1800 737 732

To speak to a Lifeline Crisis Supporter, phone 13 11 14

Watch the full episode of 60 Minutes on 9Now.