She remembers that employee – Victoria Comrie Cullen – pulling her into a treatment room one day and showing her the bruises up and down her arm.

And she'll never forget Mrs Cullen's deluded and aggressive husband erecting a sign outside the salon in an attempt to slander his wife, who had recently left him.

"He was so angry he couldn't control her any more," Mrs Arciuli-Collins said.

"That is what anger does: it makes them capable of things they didn't think they were capable of."

It was the steadily increasing displays of abuse that prompted police to take out an apprehended domestic violence order protecting Mrs Cullen from her husband, carpenter Christopher Cullen.

But within three months of taking out that order, Mrs Cullen, a 39-year-old mother-of-three, was dead.

She had been assaulted and bundled into the boot of a car before her husband bought knives on his way to a Taren Point fishing club car park, where he stabbed her several times and cut her throat, in January, 2014.

Scratch marks found on the inside of the car boot provided a horrific insight into Mrs Cullen's final struggle.

Her husband was sentenced to a maximum of 30 years in jail last year after being found guilty of murder.

Mrs Cullen is an example of the one in three intimate homicide victims killed by their partners – either current or former – in NSW when an AVO is in place.

A recent NSW Bureau of Crime Statistics and Research (BOCSAR) study into intimate partner homicides suggested a majority of the victims and offenders didn't come to the attention of police for domestic violence before the murder.

However, some do.

Leila Alavi. 26, took out an AVO against her estranged husband, Mokhtar Hosseiniamraei, who recently pleaded guilty to murder, before he stabbed her with a pair of scissors in an Auburn car park in 2014.

If found guilty, others may join this category.

Sharon Michelutti had years of AVOs protecting her from her partner, Gavin Debeyer, before he allegedly stabbed her at their Riverwood home in February.

Jamie Christopher Walker had AVO restrictions preventing him from going within one kilometre of his partner Linda Locke's Quakers Hill home, before he allegedly killed her in April, 2015.

In 2012, police took out an AVO protecting Tamworth woman Johann Morgan from Troy Jason Ruttley. In December, Ruttley – an ex-partner – was charged with her alleged murder.

In an overwhelming majority of cases, experts say, AVOs are very effective.

However, with 32.5 per cent of intimate partner homicide victims over the past 10 years killed on a background of AVOs, does more need to be done to strengthen the AVO system?

In the case of Irish-born Mrs Cullen, who had little money or support network in Australia, she was often rebuffed from shelters and told because she had a job or hadn't been recently assaulted, her case wasn't urgent enough.

Mrs Cullen, with only the clothes on her back and a garbage bag full of her possessions, left her husband in late 2013.

After her boss and confidant Mrs Arciuli-Collins co-signed a lease on a Sutherland apartment for Mrs Cullen to move into, she saw Mr Cullen's alarming behaviour escalate.

Some people urged Mrs Arciuli-Collins to stay out of Mrs Cullen's business, a reflection of a slowly changing societal view that keeps domestic violence behind closed doors.

"I thought 'I can do what's right or I can take the easy road'," Mrs Arciuli-Collins, from Sydney's north shore, said.

"And I couldn't take the easy road. This woman needed help."

After Mr Cullen's relentless phone calls and posting of degrading signs outside his estranged wife's workplace, an AVO was put in place.

It is at this point in the system, Mrs Arciuli-Collins believes, counselling intervention should occur.

"This behaviour left untreated, the only way it is going to end is death," Mrs Arciuli-Collins said.

"AVOs need to have stronger protection ... if there has been substantial proof that this woman is in danger, there needs to be intervention of some sort that takes [the man] away and gets them help.''

It is a sentiment solicitor Ian Ross, who acted for Mrs Cullen before her death, echoes.

"It seems to me what we could be thinking about doing, for men in particular, is the court has the power to force you to do some counselling courses," he said.

BOCSAR director Don Weatherburn says while there are distressing cases where an AVO does not stop a perpetrator, it doesn't underline the value of an order.

Dr Weatherburn said in the past researchers found an overwhelming majority of women who reported a domestic assault to police had an AVO.

It was then a bit surprising to see a smaller proportion for homicide victims, which underscored the difficulty of predicting a homicidal attack, he commented.

The state's top crime statistician also threw weight behind a greater focus on perpetrator programs as a way of addressing domestic violence.

"I think we have paid [an] enormous amount of attention to victims and making sure they can escape and making sure they have somewhere they can go but we haven't done near as much to try and change the behaviours of men, other than lock them up," he said.

Last year, the state government announced a $60 million program focused on domestic violence perpetrators, including a $20 million investment in behaviour change programs.

Mr Ross, who regularly acts in cases involving family law and domestic violence, said in the vast majority of cases, AVOs had a very "salutary effect".

"There is that small number who it doesn't matter to and once they are determined a piece of paper won't stop them," he said.

"I am optimistic in the vast majority of incidents that the AVO does work. Unfortunately with someone like [Christopher] Cullen, it doesn't work but I don't think it's the fault of the system."