We now know what happened in the final moments of Lilie James' life.

Lilie James was seen smiling minutes before she was brutally murdered by her former partner and colleague inside an elite Sydney private school's bathroom.

The 21-year-old had ended her brief, casual relationship with Paul Thijssen just days before her murder on the evening of October 25, 2023.

As she tried to move on with her life, her former boyfriend stalked her, carefully planning to kill her. He planned it so methodically that he even rehearsed doing it, a coroner has been told.

Hours after Lilie's death, the 24-year-old threw himself off a cliff.

But there were glaring red flags in Thijssen's past. Now, a coronial inquest is exploring their deaths and Thijssen's history of stalking and controlling behaviour before he bludgeoned Lilie to death.

Just today, CCTV of the moments before her death were played in court.

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A 'calculated' killing.

Thijssen, a colleague in the St Andrew's Cathedral School sports department, was wanted by police for questioning over Lilie's death before his body was recovered from Vaucluse on October 28.

An inquest into their deaths began on Tuesday and started with a chilling revelation. Counsel assisting the NSW Coroner, Jennifer Single SC, told the inquest Lilie's murder was calculated.

Single said that when Lilie ended the relationship, Thijssen became obsessive. He went as far as practising his attack to make sure he would get it right.

"In the days after [she broke up with him] … the evidence indicates that Paul stalked Lilie," she said.

"Paul carefully planned his attack, and that in the hours before the attack, he rehearsed the attack, making a number of dry runs.

"The preparation was calculated. It was not a momentary loss of control. It was a premeditated killing."

Lilie's chilling final moments.

CCTV footage played at the inquest on Wednesday showed Lilie smiling and going about her day, then casually chatting with Thijssen, completely unaware of what he was planning.

In the video, the 21-year-old is holding a swimsuit as she heads towards the gym bathrooms. She stops to look at a sign blocking off one of the bathrooms, a sign Thijssen had put there earlier that night, before walking into the disabled bathroom.

Thijssen is then seen standing outside the bathroom, a hammer in his right hand. He appears to glance straight at the CCTV camera before rushing in two minutes later.

Earlier footage from that night shows Thijssen practising the attack outside the bathroom, switching the hammer between his hands.

He's also seen disabling the automatic sliding doors, which Single said suggested he was trying to stop the school cleaners from interrupting him.

"No matter how many times you see that footage, it is not easy to watch," she said as her voice broke.

Lilie was remembered by her students as the sweetest person. Image: Facebook.

Thijssen stalked another ex-lover.

The inquest also revealed the Dutch-born man's history of stalking a prior partner in 2021.

His eight-month relationship with an 18-year-old known as Freya started off positive. She gave him a bundle of handmade vouchers before an anniversary, and her parents thought he was polite, friendly and respectful.

But soon Thijssen's true colours came to light.

Early in the relationship, Thijssen asked Freya to share her iPhone location with him. When she turned it off, he would "blow up" at her, the court was told.

He asked her to marry him, having earlier been warned by Freya she would not have sex with him before marriage.

She found the relationship "suffocating" and said she felt he was trying to "pressure… and control" her — this was despite him having returned to the Netherlands at this point.

The woman recalled her parents "lost it" when Thijssen suggested she travel to the Netherlands or meet him in Singapore.

When Freya decided to end their relationship and removed photos of him from her social media, Thijssen told her he was coming back.

She eventually blocked him but Thijssen allegedly hacked into her Snapchat, continuing to message her.

Students of St Andrew's Cathedral School lay flowers at the entrance to the school after Lilie's death. Image: AAP.

Following their break-up, Thijssen immediately applied for a work-holiday visa with fraudulent documents and turned up unannounced at her church that Sunday.

When Freya broke things off in person, the court was told he punched branches close to her head, telling her, "I can't punch the one thing I want to."

Soon after, she saw Thijssen watching her from a laneway near her home, and her father threatened to take out an AVO against him.

He later appeared remorseful during a meeting with Freya's father, Single said, describing no further contact after that.

Single underlined the relationship's apparent importance to Thijssen, who took the handmade vouchers to the spot where he killed himself after murdering Lilie.

"Paul still had these vouchers two years after his relationship with Freya," she told the inquest on Tuesday.

"The fact they were found 10 metres away from his backpack (left at the clifftop) leads to an inference he was looking at them before his death.

"We submit these held special significance for him."

Single described a 'web of lies' that Thijssen spun about his life in Australia. Lies that duped friends, housemates, his employer and Australian visa authorities.

This included Thijssen saying he was enrolled at university when he was actually on a working holiday visa.

While the causes of Lilie's and Thijssen's deaths are known, "the matters which led Paul to act the way he did are not", Single said.

"It's important to understand what happened to Paul to understand what happened to Lilie."

The body of Paul Thijssen was found in Vaucluse. Image: AAP.

'She always put others first.'

In the wake of her death, Lilie was remembered as a "beautiful" person.

At just 21, her life was only beginning. She was studying at Sydney's University of Technology, and was due to graduate with a Bachelor of Management in Sports Business at the end of the year.

Her coaching students described her as the sweetest person.

"She always put others first," one student told 7NEWS after her death. "She would always have something nice or funny to say. She was always encouraging everyone at sport to have a go or try something new."

Lilie was so loved. By her heartbroken parents, Jamie and Peta. By her little brother Max. She was a granddaughter. A niece.

"We are devastated and heartbroken by the loss of our beautiful daughter Lilie James," her family said in a statement.

"She was vibrant, outgoing and very much loved by her family and friends."

Lilie James' parents said they were devastated by their loss. Image: 60 Minutes.

The inquest will delve into the circumstances surrounding both deaths and broader issues such as coercive control and unacceptable behaviour in relationships in hopes of preventing similar deaths.

Thijssen's family says it has evidence his life had "become derailed" but that information has not been provided to the coroner.

NSW state coroner Teresa O'Sullivan will consider issues such as the role of technology in relationships and how to improve public understanding of ways to identify damaging behaviour in relationships.

The coroner will also attempt to determine whether authorities could have intervened at any point before the pair died.

The inquest continues.

-with AAP

Feature image: Facebook.