Rachelle Yeo was jumpy, anxious and afraid of being left alone before her former lover allegedly stabbed her to death, a Sydney court has heard.
Paul Darren Mulvihill, 44, is accused of murdering his former girlfriend Ms Yeo in her North Curl Curl home in Sydney's north in July 2012.
Mulvihill has pleaded not guilty and says he was acting in self-defence when he stabbed Ms Yeo.
The two had struck up a romantic relationship while they were both working for pharmaceutical company, Sanofi Aventis.
But after the affair soured, Ms Yeo was afraid Mulvihill was intent on blackmailing her, former colleague Renee Ward told the Supreme Court.
"She said he had bailed her up in the car park and had threatened to ruin her career," Ms Ward told the court.
Ms Ward said a teary and nervous Ms Yeo told her that Mulvihill had threatened to show sexually explicit text messages she'd sent him to the company's HR department.
After Ms Yeo confided in her, Ms Ward said she regularly walked Ms Yeo to her car on days Mulvihill was in the Sydney office so she wasn't alone.
She recalled Ms Yeo having to hang up during one phone conversation about her scorned lover's behaviour because she seemed to be having a panic attack.
"She called me back later. She was basically having some sort of anxiety," she told the court.
In another incident, Ms Yeo told Ms Ward she'd burst into tears after a friend tapped her shoulder because she thought it could've been Mulvihill.
Former boyfriend Robert Hunt said Ms Yeo was checking locks and peering through her apartment peephole in the days before her death.
The court heard Ms Yeo deliberately switched hotels from the company's usual choice while on a business trip to Melbourne after discovering her former lover had booked it too, fearing he was keeping tabs on her through a mutual friend.
The court also heard from neighbour Daryl Byron, who said he'd heard a row "broadcast to North Curl Curl" the night of Ms Yeo's death.
He said he heard a man going "berserk" before a woman screamed "leave me alone" coming from a nearby property.
"I was trying to listen for someone to go 'crack' and punch her in the face," he said.
"It was totally out of control."
The trial continues.