During her brief relationship with the man who would become her killer, Lilie James' friends only glimpsed snippets of his controlling, obsessive behaviour.
Only after the 21-year-old's brutal murder did they learn the true extent of Paul Thijssen's disturbing attempts to monitor her every move.
Ms James, a beloved water polo coach, was murdered by her ex-boyfriend inside a bathroom at St Andrew's Cathedral School, where they both worked, on the evening of October 25, 2023.
Thijssen, 23, bludgeoned her to death with a hammer he borrowed from his housemate, striking her more than 25 times and leaving her unrecognisable.
The killing was the culmination of days of careful planning, during which Thijssen was captured in eerie footage as he tested hammers and practised lunging into the school bathroom with a weapon in hand.
The planning began not long after Ms James decided to end their casual two-month relationship and ended when Thijssen took his own life in Sydney's eastern suburbs.
An inquest into the deaths of the former couple has highlighted fears about the normalisation of behaviours such as location sharing, constant check-ins and jealousy in relationships.
When Ms James had previously tried to break up with him, Thijssen lashed out with degrading, derogatory and manipulative language to control her and undermine her autonomy.
The pattern of coercive control escalated when he shared a private image of Ms James with two of his friends in a move experts say was designed to reassert his dominance.
The fact that only one of those friends mentioned the photo to police after Thijssen's death shows how normalised this behaviour has become, domestic violence expert Kate Fitz-Gibbon said.
Thijssen was also seen obsessively checking Ms James' location on social media platform Snapchat when she was at a party with an ex-boyfriend, having earlier asked a friend to monitor her.
He had exhibited similar possessiveness during his previous relationship, in which he demanded his girlfriend Freya share her location with him.
Thijssen would become upset if she turned off the function or didn't answer his calls and texts immediately, Freya reported.
Digital monitoring is a recognised form of coercive control but it's not well understood by young people, Professor Fitz-Gibbon said.
While it could be assumed Thijssen was worried and checking up on Ms James out of kindness and love, his actions were instead an indication of unhealthy and risky behaviour, she said.
Research conducted by the Social Research Centre found more than one in eight Australians thought constantly checking up on someone was caring, and more than one in 10 thought it was reasonable to expect to track a partner during relationships.
Australia's eSafety Commissioner, Julie Inman Grant, warned the inquest that people would be amazed by the "tremendous creativity a calculated perpetrator can find to misuse technology."
Ms James' death highlighted the need to educate young people about the dangers of controlling behaviour and technology assisted abuse, Prof Fitz-Gibbon said.
"Sometimes it's not love, it's coercive control," she said.
While some of Thijssen's problematic behaviour had been normalised, his escalation presented an opportunity for his friends to call him out, domestic violence expert Anna Butler said.
Police had not been made aware of Thijssen's stalking and controlling behaviour in the lead up to Ms James' death, but his friends had seen flashes.
Ms James probably hadn't seen or identified the red flags that were so visible with hindsight, forensic psychologist Katie Seidler said.
The 21-year-old was unaware Thijssen had punched a tree during his breakup with Freya and stalked her at her family home.
He repeated the pattern with Ms James, stalking her seven times over four days after she told him she wanted to split up.
Yet Thijssen had no history of aggression or indicators of violence to predict his fatal assault on Ms James, Dr Seidler said.
Nothing could have been done to prevent the unforeseen tragedy because it was the first and final act of violence, forensic psychiatrist Danny Sullivan added.
Although Thijssen had characteristics of a "brittle narcissist", Dr Seidler and Dr Sullivan agreed there was no basis for a diagnosis of a mental illness or personality disorder.
Dr Sullivan hypothesised that Thijssen hated Ms James for rejecting him and punished her by killing her, while Dr Seidler believed the 23-year-old was a compulsive liar with a fragile sense of self who killed to protect his perfect image.
Neither expert could conclusively say why he beat his ex-girlfriend to death in a calculated and premeditated attack.
They called for better education and awareness around gender-based and domestic violence, with a particular focus on changing the understanding of masculinity and relationships.
Their plea was echoed in a heartfelt statement from Ms James' parents, Peta and Jamie, who stressed the need for cultural change to prevent more women being killed.
"As parents, if we are not teaching our sons how to respect a woman's opinions and choices and accept rejection, we could be setting our daughters up for failure," Mrs James said through tears.
"In our case, a moment in time we will never recover from."
Coroner Teresa O'Sullivan said she was sure the participation of Ms James' family in the inquest would save lives.
She will hand down her findings at a later date.
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