Eight deaths in 18 months means the City averaged 3.18 homicides per 100,000 residents annually over this period.
The result is in contrast to the national rate of 1.29 last year, as calculated using figures from the Australian Bureau of Statistics.
Homicides include murder, manslaughter and grievous bodily harm resulting in death.
Police district superintendent Charlie Carver emphasised the erratic nature of homicide rates, saying it was ‘extremely hard’ to prevent unexpected jumps.
‘It’s very hard to do something before it happens, it’s happened and then we get the call,’ he said.
‘It’s sad for everyone involved.’
But he said police had preventative measures in place to drive down the ‘violent attitude’ that leads to fatalities.
Officers identify people at risk and those considered to have the propensity for extreme violence.
The approach helps prevent issues escalating to the point of tragedy.
‘No doubt we have (stopped homicides) in the past, but we’ll never know (how many),’ he said.
A spokeswoman for Police Commissioner Karl O’Callaghan said statistics viewed in isolation were misleading.
The City of Wanneroo’s homicide rate was much lower when viewed over a 10-year period, with 18 deaths in the last decade to July this year.
‘All of these homicides have been solved, with accused persons being charged in each case,’ she said.
‘Every year there are around 40 homicides in Western Australia and, in most cases, the offender is known to the victim.
‘From time to time, there may be unexplained spikes in the incidence of crime, including homicides.’
Six of the eight homicides in the 18-month period were unrelated, with the alleged Girrawheen double murder of Vanesa Farcich (31) and Saso Filkovski (37) in May this year being the only connected incidents.
The spate began with the Wanneroo shooting murder of Jeremia Iskander (21) in December, 2011.
This was followed by the alleged Wanneroo murder of David Blenkinsopp (30) in March, 2012.
In June last year, Jason Burton (41) was shot dead in a Clarkson manslaughter incident.
Two months later, police alleged Phaea Lightfoot (51) was murdered in a Wanneroo shooting initially reported as suicide.
In February this year, Rita Addenbroke (59) was run down by a car and killed in an alleged manslaughter incident at a Madeley caravan park.
Then in April, police alleged William Maker (29) was murdered when he was hit by a car in Merriwa.
Supt Carver reiterated the fact police charges had resulted from each investigation.