Half of female homicide victims 18 or older are killed by a partner or ex-partner.

Heidi Welman-Scott died on the front lawn of her North Shore home after a frenzied knife attack by her estranged husband, Brent Scott.

Scott was so determined to kill Welman-Scott, he stabbed her daughter and daughter's boyfriend when they tried to intervene. Both survived serious injuries.

Like many other similar crimes of intimate partner violence, Scott’s attack was not a spontaneous act, but a highly calculated and planned murder.

Scott booked a flight to his native South Africa months in advance and bought the knife four days before sneaking into Welman-Scott’s garage and murdering her as she returned from a night shift at the Southern Cross hospital in North Harbour.

Scott was arrested at Auckland Airport as he attempted to flee.

The Homicide Report analysed 1125 homicides in New Zealand between 2004 and 2019.

The circumstances of Welman-Scott’s death are reflected in dozens of other cases.

Our analysis reveals that every eighth homicide victim in New Zealand is a woman who dies at the hands of a boyfriend, partner, husband or ex-partner. These account for half of female homicide victims 18 or older.

Such cases are often among the most violent homicides. The victims are more likely to be stabbed or asphyxiated than other homicide victims.

Family Violence Death Review Committee data shows that 50 per cent of intimate partner violence homicides are overkill deaths – when a killer inflicts injuries far beyond what is required to kill.

Overkill predominantly occurs in cases in which the victim had separated or was planning to separate from the offender.

There is a tendency for these homicides to be premeditated or planned rather than spontaneous or unintentional killings.

For the other half of adult female victims not killed by a partner or ex-partner there are fewer common factors linking the deaths.

Family violence is still a big contributor with 32 women (11 per cent) dying at the hands of a family member. Meaning family violence is at play in 60 per cent of homicides in which the victim is female and 18 or older.

The next biggest relationship between victim and killer is "stranger", accounting for 16 per cent of the homicides. However, the cause of death in 31 per cent of these cases is a car crash.

Once the car crashes are excluded, there are 33 separate instances of a woman being killed by a stranger in some form of homicidal attack over the 16-year period we analysed. A rate of two per year.

Although they often get a lot of public attention, this type of homicide is a relatively rare occurrence in New Zealand.

More than a quarter of adult male homicide victims are killed by a stranger.

A single punch was all it took to end Filipo Sipaia’s life.

Ultimately it wasn’t the punch that killed him, but the fall.

Sipaia was knocked unconscious by Jonathan Ioata after a fight broke out between two groups of friends in Lower Hutt in August, 2011.

He punched Sipaia in the side of the head, he fell, the hard ground broke his fall and he never woke up again, dying in Wellington Hospital the following day.

Like so many other similar deaths in New Zealand, Iota never intended to kill Sipaia, only to hurt him.

In sentencing him to four years and nine months in prison following his manslaughter conviction Justice David Collins described Iota as “… sadly typical of young men in New Zealand, with a poor upbringing, limited education, alcohol issues and with a testosterone fuelled belief they were bulletproof.”

Justice Collins’ sentiments are reflected in our analysis of 1125 homicides.

Men account for a disproportionate number of New Zealand’s homicides victims – 56 per cent in the period of our analysis.

The most common relationship between the men who are victims of homicide and their killers, is not really a relationship at all.

More than one in four (28 per cent) did not know their killer, compared with 16 per cent among women.

Gunshot is the most common cause of death in these homicides – a man dying at the hands of someone they do not know – accounting for 74 (42 per cent) of the victims in these circumstances. This number is inflated somewhat by the 45 adult men killed in the Christchurch terror attack.

Isolating the remaining 136 cases of male on stranger violence in our database, we see that blunt force trauma accounts for 38 per cent of victims, 24 per cent were shot and 18 per cent cent were stabbed.

In 38 per cent of these cases we were able to determine that alcohol was a factor.

One in eight victims of homicide in New Zealand is under the age of 15.

The Homicide Report shows yet again the extent of New Zealand’s shameful child abuse record.

Stuff’s Faces of Innocents project highlighted New Zealand’s horrific rate of child homicide and examined the root causes and possible solutions.

We are now able to put these homicides into the context of all homicides in New Zealand.

In all, there have been 139 victims under the age of 15 between 2004 and 2019, one-eighth of all homicides between January 2004 and March 31, 2019.

Overwhelmingly, the killers of these children are the very people who should be looking after them.

While Faces of Innocents focussed on victims aged 14 and under, The Homicide Report also analysed the deaths of 15 to 17-year-old victims. There were 58 homicides of young people in this age bracket, accounting for about six per cent of the victims.

Cheyenne Smith-Grey, a 17-year-old car crash victim, is among those killed. Described as a "charismatic" teenager with a big future in front of her, Smith-Grey was thrown from a car and killed on the outskirts of Hamilton in 2012. The driver, Cyrus Ormsby, was affected by alcohol and was speeding. He was convicted of manslaughter.

Car crashes like these are the single biggest cause of homicides for 15 to 17-year-olds in New Zealand, accounting for 38 per cent.

For car crash victims to be included in The Homicide Report database, someone has to be charged or convicted of manslaughter or murder.

The most common relationship of victim to killer is friend.

Young men account for more than a third of homicide offenders in New Zealand.

Homicides are overwhelmingly committed by men, in particular young men, who account for the greatest proportion of fatal violent crime in the country.

Eighty-seven per cent of homicide offenders are male. Almost half of those are 30 or younger.

The younger the age group, the higher the prevalence of offenders. In fact 18 is the most common age to kill. Between 2004 and 2019 there were 37 18-year-old men who committed homicide.

Alcohol is a factor in at least 40 per cent of homicides in which the killer is aged 30 or younger.

Māori are the ethnic group most disproportionately represented, accounting for 44 per cent of offenders. Poverty and deprivation appear to be the driving force behind this statistic. We know from our previous work that 10 times more homicides occur in the most deprived neighbourhoods than the least deprived. There are many more Māori living in deprivation.

Eighty-eight per cent of killers have a previous conviction for violent crime. On average they have three convictions each. Some have many more.

The analysis is based on previously unreleased data supplied to The Homicide Report by police. It includes information on the age, gender, ethnicity and number of prior violence convictions for more than 800 killers.

By matching offenders with their victims, we were able to match some of the victim data from The Homicide Report database to each killer in area like cause of death, killer-victim relationship, location and social deprivation.

The data has allowed us to look at the characteristics of offenders in the key ‘types’ of homicides we identified in the launch of The Homicide Report, when we focussed almost entirely on the victims.

One of the key findings was that half of adult female victims die at the hands of a partner or ex-partner. We now know the offenders in these homicides are older, on average, than other killers.

And partner/ex violence is more common across all levels of society than other types of homicide, although it is still skewed to the more deprived parts of the country.

Other types of family violence (predominantly that committed against children or young people) is more closely linked to deprivation. The killers in these cases are more likely to be Māori and generally much younger than those who kill their partner or ex-partner killers.

The most common relationship between an adult male victim and his killer is a stranger. This is another key cluster of homicides we previously identified. The offender data shows us the median age of these killers is just 24.

Eighty-eight per cent of them have a prior violence conviction. The average number is three violence convictions before killing.

Gun deaths was another focus of our initial work on the Homicide Report. An analysis of offenders shows that men pull the trigger in almost all gun homicide incidents, that 55 per cent of them are under the age of 30.

Alcohol is a factor in nearly a third of homicides in New Zealand.

Cody Cribb pleaded with his friend Ricky Vanstone to slow down as he sped along a rural road near Taumarunui one evening in 2011.

Moments later Cribb would be dead, killed instantly after they collided with an oncoming ute.

Earlier that night he and some friends had been drinking at a party. They left with Vanstone, a repeat drink driver who was two-and-a-half times over the legal limit, behind the wheel.

At his sentencing for manslaughter Justice Pamela Andrews read out a letter from Vanstone, in which he said the crash would “hang over me for life”. The judge agreed, saying: "Your driving caused the death of one of your best friends, you will have to live with that for the rest of your life."

Like so many other homicides in New Zealand alcohol contributed to Cribb’s death.

It wasn’t the only factor - the speed Vanstone was driving and the poor condition of his vehicle contributed too. But like many other homicides it is hard to conclude the death would have occurred without the presence of alcohol.

For The Homicide Report we were able to determine that alcohol was a factor in 347 homicides between 2004 and 2019, 31 per cent of the total.

The actual figure is likely to be higher because there are many homicides in which we suspected alcohol played a part but were unable to confirm it.

In these 347 homicides alcohol was not always the main or even secondary cause, but in case after case it was there in the background.

It might inflame the tensions at a party, bring out the worst of someone’s violent tendencies or, as in the case of Cribb’s death, cause someone to get behind the wheel drunk.

Deaths with characteristics like Cribb’s make up a significant subset of homicides: car crashes in which the victim was under 30, the killer was a friend and alcohol was involved. In fact, we identified 38 cases with these exact characteristics.

Alcohol also touches many of the other issues we have highlighted in The Homicide Report.

When a man dies of blunt force trauma, alcohol is a factor 48 per cent of the time.

It contributes to people killing those who are close to them. When the victim-killer relationship is "friend", alcohol is a factor 64 per cent of the time.

The homicides which involve alcohol are also skewed significantly towards young people.

Alcohol is a factor in 39 per cent of homicides in which the victim is in their 20s, compared to 28 per cent for victims 30 and older.

Homicide is nine times more likely to occur in neighbourhoods with high levels of social deprivation.

The Homicide Report examines 1125 homicides in New Zealand between 2004 and 2019.

The Social Deprivation Index divides the country into deciles (10 per cent buckets) based on how deprived they are.

We tallied up the number of homicides that occurred in each decile and found that homicide is nine times more likely to occur in a socially deprived neighbourhood than it is in an affluent one.

One in five homicides occur in the 10 per cent of most deprived neighbourhoods and just two per cent occur in the 10 per cent of least deprived neighbourhoods.

Not every victim who dies in a deprived neighbourhood is themselves deprived, nor necessarily is their killer. But there is a clear relationship between where violence occurs and where social deprivation is apparent in New Zealand.

In the map of Auckland below, darker colours signify higher levels of deprivation and vice versa. The points show the locations of homicides.

The map confirms that most of the homicides in Auckland occur in areas with high social deprivation.

The most concentrated cluster of dots near the centre is the neighbourhood of Otahuhu West, which is in the four per cent of most deprived neighbourhoods in New Zealand.

You can use the map to explore the other main centres, where the same relationship is apparent.

Auckland

Auckland

Hamilton

Wellington

Christchurch

Dunedin

What do we know about the differences between homicide victims from deprived areas compared to those in less deprived areas?

Two clear trends stand out: Victims in deprived areas are more likely to be men.

And they are more likely to die as a result of blunt force trauma or stabbing. These two causes account for the vast majority of the additional homicides that occur in more socially deprived areas.

The Al Noor Mosque, in which 45 people were killed in the Christchurch terror attack, is in an area in decile 6 of the Social Deprivation Index, which is why this decile bucks the trend in the graphics.

Two thirds of gun homicides are committed with .22 calibre rifles or shotguns.

Bradley Lomax met a brutal end on a shingle track near the Waimakariri River north of Christchurch in September 2017.

Lomax was taken to the secluded location on the pretext of a methamphetamine deal by the men who would eventually be jailed for his murder – William Gosset and Cody Derek Martin.

Once there, Lomax was shot in the leg with a shotgun, then shot in the head with several rounds from a cut-down .22 rifle, before another shotgun blast hit him in the upper arm and chest.

Lead investigator Detective Inspector Greg Murton said Lomax's death was "as brutal as any killing you will see".

Gosset and Martin both claimed the other man fired the fatal shots.

The victim and his killers were Christchurch underworld figures, described by police as “fairly typical of low to mid-level drug dealers”. Neither of the killers was licensed to own a gun.

There were 118 gun homicide incidents - a total of 175 victims - that occurred between 2004 and 2019 (excluding hunting accidents and police shootings).

Many of them share key characteristics of Lomax’s murder.

Two thirds of gun homicides in New Zealand are committed with shotguns or .22 calibre rifles. In many cases, these weapons were cut down or modified in some way.

Military-style semi-automatics (MSSAs) accounted for at least 28 per cent of the victims who died. The majority died in the terror attack at two Christchurch mosques on March 15, underlining the deadliness of these weapons, despite incidents involving them being rare.

Only a small minority of those who kill with a gun hold a licence – about 12 per cent. In 63 per cent of gun homicides we were able to determine the killer was not a licensed gun owner – this does not count a handful of recent cases for which we have yet to obtain licensing information.

About 30 per cent of gun homicide incidents had some kind of connection to gangs or the criminal underworld. There appears to have been an upswing in these cases, with a spike of seven shootings with criminal or gang connections in 2018 and at least five in 2019.

Nearly all gun-related homicides were committed by men. Men also account for 75 per cent of the victims of gun violence.