WARNING: Distressing content
THE most violent of all parents who kill their children is the stepfather or de facto partner, according to research.
He kills by throwing or stomping the child, but he usually only kills a single victim.
More deadly is the separated father who, a study by Swimburne University in Melbourne has revealed, kills multiple victims - often all his children - in a bid to punish their mother.
But the most deadly of all parents who kill their children is the coupled father, who is still living in the family unit.
He will kill multiple family members, not only his children but also his wife is in danger of being murdered with her kids.
Killing season for kids can come at any time of year but when it comes to mothers, fathers or stepfathers who murder children there are five distinct types.
This is the conclusion of a new study of filicide - the act of a parent killing their child -
by Lillian De Bortoli, a research fellow at the university's Centre for Forensic Behavioural Sciences Australia.
During her research, Dr De Bortoli studied 155 murders perpetrated by 97 parents in Australia between 2000 and 2011.
Of the victims, 118 were children said Dr De Bortoli, who selected child murders carried out by single perpetrators from coronial cases of child deaths around the country.
Her analysis of those statistics reveals a chilling similarity between the method and number of victims and five "types" of parent who murder their child.
"I looked at all the kids who died and I identified patterns, whether they were mothers, fathers and coupled or single at the time of the killing," Dr De Bortoli told news.com.au.
The different types are the de facto male or short-term stepfather, the separated father, the single mother, the "coupled" mother who is still in the family unit and the coupled father.
"The de facto male kills in a particularly violent way," Dr De Bortoli said. "He inflicts multiple abdominal injuries, and head and spinal injuries, and he has usually been abusing the child for some time before he kills them.
"The separated father kills multiple victims.
"He has a background of interpersonal violence, and has been violent to the mum which is why they separated."
Dr De Bortoli also uncovered patterns in how people murdered their children according to the age of the child.
"The little ones often suffer head or spinal injuries," she said, adding that seven or eight-year-olds were sometimes suffocated after being drugged. "Also there are cases in which the parents has used carbon monoxide poisoning," Dr De Bortoli said.
Presenting her findings at a recent international conference in Italy, she said that compared to other countries, a very high number of Australian parents - 27 per cent - who murdered their children went on to kill themselves.
Dr De Bortoli was motivated to do the research because of a dearth of statistics available on Australian child deaths, compared with abundant publicly available studies in countries such as the UK and Canada.
"We have to get a much better way of monitoring and understanding child death with a view to preventing it," she said.
"The difference between death and serious injury can be like the flip of a coin.
"Sometimes the child doesn't die because the mother has come home in time and taken her child to emergency and the child has lived.
"But put yourself in the shoes of a child protection practitioner.
"Identifying which child is at risk is a difficult call to make, and sometimes you can cause more harm by taking the child away from their parents."
Dr De Bortoli said understanding how a parent could inflict pain on their own child was not part of the study, but the cruelty of the deaths often angered her and made her think about the children who survived.
"We need more support for kids who have been abused, who have these tough childhoods and may end up on the street or in the criminal justice system," she said.
"And people who kill their children may have personality disorders, or their empathy is not well developed.
"This occurs in people who have been abused as children or may have had a traumatic childhood."
Dr De Bortoli will publish her study in an international journal, making her findings available to child protection agencies in Australia and overseas.
Here are the five distinct types of parents who kill their children and characteristics of their crimes:
DE FACTO MALE
Is in a relationship with the mother of the child he kills.
Kills in a violent way.
Usually has only a single victim and has abused the child for some time before killing them.
The abuse may begin with the man shaking a crying child because he is angry that he cannot sleep or watch TV.
Method of killing the child can include stomping on or throwing the child, inflicting multiple abdominal injuries and head or spinal injuries.
Rarely commits suicide after the murder.
Victims are usually young children.
Laughing at his own luck, Matthew Scown caused national outrage when he was pictured walking free on early release from prison last week after pleading guilty to killing Tyrell Cobb.
The four-year-old had died in agonising pain in 2009, but Scown's plea deal secured the Queenslander a reduced sentence.
Scown had become the de facto partner of and Tyrell's mother, Heidi Strbak after she moved with her young son to the Gold Coast.
The couple had been together for less than a year when Tyrell died in May 2009 from internal bleeding and abdominal injuries caused by blunt force trauma.
A post-mortem revealed he had 53 bruises and 17 abrasions from head to legs when he died.
Scown was charged with murder a day after the boy's death in 2009, but the case was dismissed at a committal hearing in 2010.
This month he pleaded guilty to manslaughter and was sentenced to four years, but released immediately for time served on remand.
Amateur boxer Christopher Hoerler met Louise Anderson on New Year's Eve, 1999 when little Jordan Anderson-Smith was a happy and healthy five month old boy.
But for that fact, baby Jordan's existence might never have made headlines and he could have just celebrated his 18th birthday a few months ago.
Instead the horrific end to Jordan's short life can be summed up in his devastating post-mortem report.
The seven-month-old suffered toes crushed by a fan clamp, broken ribs, a cut liver, a bruised pancreas and a torn lip.
He was tortured and killed after a party at Ms Anderson's Wagga Wagga home.
Louise had separated from baby Jordan's father, Cecil Smith, and 26-year-old Hoerler moved in with her in early January 2000.
After drinking and smoking cannabis, Hoerler claimed he heard a thump in the night and woke to find baby Jordan on the floor with red, brown and white fluid frothing from his mouth.
Bloodstains were splattered on the wall of the main bedroom, the baby's cot sheet and on Hoerler's blue Nike shorts.
An emotional Cecil Smith and his family farewelled Jordan in a tiny white coffin.
Twenty months later police charged Hoerler with baby Jordan's murder.
On trial in 2003, Hoerler pleaded guilty to the lesser charge of manslaughter.
Granted parole in 2014, Hoerler was deported back to Papua New Guinea.
He played the grieving stepfather at Bailey Constable's funeral, carrying the four-year-old's coffin.
But the post-mortem on the body of the little boy with the cheeky grin who had loved Thomas the Tank Engine, showed that Nathan William Forrest had made a misery of Bailey's final months.
Bailey Constable's grandparents had fought to get child protection authorities to intervene.
Forrest was an "angry and aggressive man", a ticking time bomb on drugs.
In the weeks before his death on April 1, 2011, Bailey told his grandparents Forrest hurt him and held him down in the bath.
On the last day of Bailey's life, Forrest had been injecting methamphetamine.
When Bailey wet his bed, Forrest took him into the bathroom.
The boy's mother, Jessica Constable, hears a series of loud bangs and Forrest yelling at her son.
When Bailey emerged from the bathroom, he fell to his knees.
Ms Constable put him to bed, but when Forrest checked on Bailey later he came back saying that the boy was dead.
A post-mortem found Bailey's body covered with old and new injuries.
His forehead, cheeks and the back of his head were bruised and he had black eyes.
He had been belted across the buttocks and there were old cuts across his nose.
Forrest pleaded guilty to Bailey's manslaughter in 2013.
As Justice Elizabeth Fullerton jailed Forrest for a minimum of six years, he smiled and gave his family the thumbs up in court.
Given time served, Forrest's earliest possible release date was in May this year.
Has a background of interpersonal violence which may have caused the separation.
Kills multiple victims.
Often kills the children to punish the mother in a custody dispute.
Separated father Robert Farquharson, drove his three sons into a farm dam near his Winchelsea, Victoria home after a Father's Day access visit in 2005.
Jai, 10, Tyler, seven, and Bailey, two, drowned, but Farquharson managed to escape and said he couldn't save his trapped sons.
He claimed he had lost consciousness during a coughing fit at about 7pm and crashed through the dam fence.
Three months later police charged him with his sons' murder but even his estranged wife, Cindy Gambino said she believed "he would not have hurt a hair on their heads".
Farquharson's 2007 murder trial heard that it would have taken a 220-degree turn to manoeuvre his vehicle off the highway and into the dam, and that Jai's body was half way out the car's front door.
Farquharson's friend, Greg King, told the court that the father of three had intended to kill his children to get back at his former wife.
Mr King said two months before the incident, Farquharson had spoken of taking revenge on Ms Gambino and "take away the things that mean the most to her".
Shane Atkinson, who found Farquharson on the side of the road after the crash, said he had twice refused to call triple-0.
Instead the father went personally to tell Ms Gambino of the drownings and Mr Atkinson had to borrow a mobile phone to call police.
The day before a jury found him guilty, Farquharson who was on bail ordered three red tulips for his sons' graves and a card for what would have been Jai's 13th birthday.
Ms Gambino collapsed after the verdict and was taken from the court in an ambulance.
Farquharson is serving three life sentences without parole.
It was Easter Sunday, 2014 when Tanzanian national, Charles Mihayo, told his ex-wife he wanted to "say goodbye" to his daughters Savannah, four, and Indianna, three, and "see them one last time".
Mihayo had been fighting with his ex-wife for access to the girls since their separation.
He was angry over the failure of his marriage and held considerable hostility towards his former partner because he felt she had treated him unfairly.
Unbeknown to her, four days before the visit he had run a Google search for: "How can I kill my ex-wife".
When the little girls arrived for the access visit, he dressed them up in white and filmed them dancing to a song from the film Frozen.
Then he suffocated them.
Mihayo dialled triple-0 and took his slain daughters into the bathroom of his unit in Watsonia, Victoria to bathe and redress them before police arrived.
He told officers at the door "It's done. I've killed them. I've killed my kids".
Mihayo expressed no remorse or regret to police.
In December 2014 he was sentenced to a minimum 31 years in prison for what a Victorian Supreme Court Justice Lex Lasry described as "a hideous crime".
"You decided to demonstrate to your ex-wife that she did not have the control over the children and their relationship with you that she thought she had," Justice Lasry said.
"You decided she would pay the price and inevitably so would your children, with their lives."
Craig Andrew Merritt
Craig Andrew Merritt was the "perfect, doting father" of three children to three different mothers.
He had weekend access to all his children, six-year-old Jackson Merritt, Taylah Pringle, 11 months and Mikaylah Green, 11 weeks.
For Father's Day, 2001 the children's mothers thought it would be nice for the kids and their dad to share a visit at their grandmother's house in western Sydney.
On the evening of the visit, Merritt fed and bathed the children and dressed them in their pyjamas.
At some point he smothered them. Merritt then drank a large amount of bourbon and its seems intended to take his own life.
At 1am, he sent a text message to his then partner saying: "Good buy (sic) from me, my son and my daughters" followed by: "Good bye till next life. I've always loved U and UR sons."
But at 8am he turned up at Parramatta police station and said "I've put my kids to sleep".
He said he was a failure, having had three children to different mothers.
"I should be more like a normal family and have three children to one mother," he said. "I thought, all I want to do is try and be a good father, and nothing seems to work."
Merritt claimed not to remember the murders.
At his sentencing to life without parole, members of the public gallery yelled out: "Rot in hell, you dog" and "gutless prick".
In 2004, the NSW Court of Criminal Appeal overturned his sentence and gave him 34 years with a 27 year non-parole period.
Merritt's first possible release date is in 2028.
Generally has a mental illness, or some sort of psychosis.
Kills a child or children by asphyxiation or suffocation.
Kathleen Folbigg, now aged 50, has generally ben regarded as a model prisoner since her incarceration for suffocating her four infant children between 1989 and 1999.
A campaign for Folbigg claims she was wrongly convicted and a petition for a review of her case to the NSW Governor is currently before the NSW Attorney-General.
But Folbigg was sentenced in 2003 for the murder of her children Patrick, Sarah and Laura and for the manslaughter of Caleb.
Folbigg and her then husband Craig Folbigg's first child, Caleb, died at the age of 20 days old in 1989.
The death was followed by those of Patrick, aged eight months, in October 1990,
Sarah Kathleen, aged 10 months, in August 1993 and 18-month-old Laura Elizabeth in March 1999.
The deaths were only regarded as suspicious after the discovery of a diary in which she had written "I am my father's daughter".
Folbigg's own father murdered her mother when she was a child.
Her trial heard that she smothered her children because she couldn't cope with the stress of raising them.
Folbigg appeared in court last month to appeal a short sentence for punching another inmate in row over a toaster.
The otherwise well-behaved Folbigg who acted as a den mother to fellow female inmates, has been transferred from Silverwater maximum security prison to Cessnock jail.
Statistically fathers who are still in the family unit who kill their children are more likely to have a history in the criminal justice system.
Kills multiple family members and his wife or partner is often in danger of also being killed.
Kills by stabbing or inflicting head or spinal injuries.
News of the carnage on a propertyat Lockhart near Wagga Wagga in the NSW Riverina in September, 2014 reverberated about the country.
Four bodies were found in and around the house of the Hunt family property, Watch Hill, on September 9, 2014.
Kim Hunt, 41, had been gunned down in the driveway.
Her three children, Fletcher, 10, eight-year-old Mia and Phoebe, six, had each died in their beds from a single shotgun wound.
The following day, police divers found the body of 44-year-old wheat and canola farmer, Geoff Hunt, in a dam near the house.
He, too, had died from a single gunshot wound.
Detectives immediately suspected what proved to be the truth, Geoff Hunt had killed his entire family and then taken his own life in a classic murder-suicide.
What was not so obvious was the motive.
Details emerged of Kim Hunt's personality change following a serious brain injury when she had rolled the family car in a 2012 accident which had left her daughter Mia largely unhurt.
The accident left the popular nurse with physical, neurological and cognitive impairments that impacted upon her family life and marriage, which had already been under stress.
Kim Hunt became "intolerant, indiscreet and abusive" by way of her brain injury.
Her husband became depressed and had expressed suicidal thoughts.
A 2015 coroner's inquest concluded that an "egocentric conclusion" drove Geoff Hunt to shoot his family.
A forensic psychologist told the inquest it's likely the farmer primarily wanted to kill himself due to his depression and a total loss of hope.
"But he believed his wife and children were dependent on him and so in killing them he was 'sparing them future pain'," concluded NSW State Coroner Michael Barnes.
"His distorted logic led him to conclude that the children and his wife would not cope without him.
"It was the result of an egocentric delusion that his wife and children would be better of dying than living without him."
From Bogota, Colombia, Maria Claudia Lutz, her engineer husband Fernando Manrique came to live in Australia.
Lutz, a criminal lawyer, gave birth to a daughter and son who were special needs kids, highly talented artists but on the autism spectrum.
They attended St Lucy's Catholic School, Wahroonga where Ms Lutz volunteered in the canteen.
The family lived in a corner house in the northern Sydney suburb of Davidson.
Beneath the surface of the friendly family exterior, was a troubled relationship between Maria Claudia and Fernando, who had been retrenched from his job at Fuji Xerox Australia.
He found a new job in a small processing logistics company which took him away from home travelling often.
He wanted to return to Colombia, but Ms Lutz refused.
On November 16 last year police attended the house after a school friend of Ms Lutz called in concern for the family's welfare after she failed to turn up for tuckshop duty.
Inside the Davidson house, police found the bodies of the two parents, Elisa, 11, and Martin, 10, as well as the family dog, Tequila.
They also found a crude bath lethal system rigged up of gas canisters and pipes into different rooms.
Neighbours had seen Manrique on the roof with power tools in the days leading up to the murder-suicide.
It has since emerged that Ms Lutz had told Manrique that she wanted a separation from him.
A friend of Ms Lutz, Sarina Marchi, told the Sunday Telegraph that just before he killed his family and himself, Manrique had displayed a drastic turnaround in his behaviour.
When Ms Lutz told Ms Marchi her soon to be ex-husband was acting like a model father, alarm bells rang.
"I said: 'This doesn't sound normal'," Mrs Marchi said. "I said: 'I know that a lot of violence happens after separation and if it doesn't feel right; if you suspect anything just get out'."
Three days later the family was dead.
Kills children from almost all age groups.
Affected by mental illness.
Generally murders a single victim.
Kills by asphyxiating or suffocating the child.
Dean Shillingsworth was a "clingy" little boy who craved attention from his mother, Rachel Pfitzner.
Since separating from the boy's father Paul Shillingsworth, who she loathed, Pfitzner had been in a custody battle with the mother of her former partner.
Pfitzner hated Ann Coffey and in October 2007, a custody order was likely to return little Dean to the care of his paternal grandmother.
Pfitzner was not coping with motherhood and she took her resulting rage out on her son.
Neighbours would hear her raging at him and on one occasion when she locked him outside in the cold, they heard him begging, "Mummy, Mummy, I am sorry."
Pfitzner often couldn't afford to feed him and she hadn't managed to adequately toilet train her son, who was aged two years and eight months.
When the hungry toddler went out to find food from others, Pfitzner would punish him for embarrassing her.
On October 11, 2007 Pfitzner finally snapped.
On a visit with Dean to friends, who could see the boy was hungry and gave him a hamburger, Pfitzner became enraged.
As she later told a prison psychiatrist, when they got back home she grabbed him by his hooded jumper and shook him until he frothed at the mouth.
When she realised her son as dead, Pfitzner stripped him naked, wrapped him in plastic bags and put his body in a tartan suitcase.
She took the suitcase to a duck pond at Ambarvale in Sydney's southwest, tossed it in and watched it sink.
Children later discovered the body in the suitcase while playing at the pond.
Pfitzner was jailed for a maximum 25 years and six months.
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