Australian study looks at what makes women kill

Women are at their most deadly when they are under financial strain — and even females who have no criminal history can be driven to murder, new research shows.

An analysis of almost 150 Australian murders by Queensland University of Technology researcher Dr Belinda Parker has shown women are more likely to kill when they are motivated by gain.

"I think it highlights perhaps an area we don't talk about enough," she told news.com.au. "We tend to talk about abuse [as a motivating factor], which is important — and I'm not trying to downplay that — but it's important to look at why these females commit the murders beyond [simply] a psychological explanation."

Her recent thesis Seven Deadly Sins identifies what is fuelling Australian homicides. It is the first of its kind to test the characteristics of murder motives and look at them side-by-side to compare each motive to one another.

NSW mother Kathleen Folbigg killed her four children. Photo / Getty

"Gain is one of seven motives that characterise the solved homicides I analysed. The others were jealousy, revenge, conviction/hate, concealment, love, and thrill,"

Properly understanding motives could then led to identifying "risk factors in people's lives".

"Especially the gain [motive]. I did see that quite a lot in my sample — the financial insecurity on the part of the females was when she acted in the cases that I observed."

It is well known that women are at risk of being killed by a lover, but Dr Parker's findings show risk factors such as a separation or divorce, or drawing up a new will, could provide warning signs for male victims.

"Homicide of a male partner is not always motivated by a history of domestic abuse, which again challenges a lot of the prior literature," she said.

In fact in all of the cases Dr Parker examined, the female killers were not the victims of abuse by their husbands.

She told news.com.au about one case she studied where a woman in her 70s killed her former partner many years after they separated.

"They'd been apart for a long time but he was going to change his will and cut her and her son out. And that's when she acted. It was years following their separation but it was the drawing of the will that made her act."

The murders that fit in the "gain" category were more carefully planned than other sorts of killings. "Things like jealously and revenge were far more frenzied and more emotionally heightened than people who kill through gain or concealment — they are far more calculated," said Dr Parker.

Katherine Knight is Australia's most savage female killer. She stabbed her partner 37 times and then decapitated him.

Females were also more likely to hire contract killers. But that didn't always mean they were successful.

"These are foiled because often the [assassins] talk to the wrong person. I'm amazed at how prevalent it is."

She said the killers and victims from her sample were mainly "average joes" with no red flags prior to the murder.

Dr Parker said that when love was the motive, killers were not acting for selfish reasons.

"Here, I found interesting interrelated results. Victims are either very young, aged between 1 and 9, or were over 50 — most often they are the children or parents of the offender and the homicides nearly always occur at the victim's home," Dr Parker said.

"When children were killed for love by a woman, it was committed out of either altruism – to spare the child a life that was perceived to be filled with pain — or extended suicide, when a parent intends to commit suicide and can't bear to leave her children or that they will not survive without them.

Four of five homicides that were in the love category were males killing their female partners. But love homicides committed outside of an intimate relationship, such as the killing of a child, was when a female was more likely to be involved.

"However, when victims were older, the typical offender was an intimate partner who assisted them to commit suicide or killed them to prevent further perceived suffering.

In her thesis, Dr Parker wrote men were still "overwhelming" responsible for the greatest number of homicides.

"Although males consistently account for the majority of homicide offenders and victims, this research indicated that females were most likely to commit homicides for gain and love but fall victim to jealously and thrill homicides."

Dr Parker examined each of the 149 homicides for the age and gender of both victims and offenders, cause of death, relationship of victims and offenders, and location.

Judy Moran after leaving the Melbourne Magistrate's court in March, 2007. She was jailed in 2011 for the killing of her brother-in-law. Photo / Getty

"Ultimately, it's hoped that these results, along with further research, might help investigators to establish motive and reduce the number of persons of interest. For example, if a male victim is older than 35 and going through a divorce the motive might be gain but if a male victim is over 65 and killed in their home, it might suggest the motive was love."

She hoped the next step was to do more research.

"It's important to get into the heads of these people and look at fundamentally why these happen."

She hoped the research would be useful to police in helping reduce the list of suspects early in a homicide investigation.

"It might lead them down a specific track or might rule something out."