A sports coach used gaslighting, stalking and abusive language to control his girlfriend before he bludgeoned her to death at the school where they worked, a coroner has heard.

Hockey coach Paul Thijssen hit water polo coach Lilie James in the head with a hammer at least 25 times inside St Andrew’s Cathedral School in Sydney on October 25, 2023.

James had ended her casual two-month relationship with the 24-year-old five days before she was killed inside the gym bathroom.

Domestic violence expert Anna Butler told an inquest on Wednesday that patterns of coercive control were evident throughout their short relationship.

When James had previously tried to break up with Thijssen, he used abusive, derogatory and gaslighting language to negate her autonomy.

He escalated his emotionally abusive behaviour when he shared an intimate image of the 21-year-old with friends and stalked her after she expressed doubts about their relationship.

Butler said he felt growing anger and resentment that he no longer controlled their status so he used a cache of well-honed manipulative tactics to try to regain his control.

Noting that some of the behaviour around jealousy and location-sharing in relationships has been normalised, Butler said it was an opportunity for his friends to call out his increasingly problematic behaviour.

Yet forensic psychologist Katie Seidler noted Thijssen had no history of aggression and there was probably nothing that could have been done to prevent the gender-based violence.

Although the 24-year-old wielded coercive control in his relationships, she found there were no obvious warning signs or indicators of violence to predict the tragic outcome.

Seidler theorised Thijssen killed his 21-year-old ex-girlfriend because he was terrified the break-up would unravel his facade of perfection.

She opined he had a fragile sense of self and saw himself as inadequate and unworthy, which led him to lie to create a flawless public image.

Issues of coercive control and unacceptable behaviour in relationships are being examined by the inquest into the deaths of James and Thijssen, who died hours after his ex-girlfriend.

Coroner Teresa O’Sullivan is assessing whether his death was self-inflicted.

Australia’s eSafety Commissioner Julie Inman Grant is set to give evidence about the role of technology in relationships, particularly those involving young adults.

The inquest will also hear statements from James’ family as it draws to a close on Thursday.

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