So too has been how to deal with the perpetrators of such grievous acts.
On Monday the government went back to the future and — as various coalition parties pledged on the campaign trail — announced that it would restore the controversial "Three Strikes" legislation.
This has been a political football for decades, as parties leaning to the right have hailed it as the "tough on crime" legislation New Zealand needs, while parties on the left decried it for its arbitrariness, perceived lack of effectiveness, and for its disproportionate impact on Māori and Pasifika people.
Those stuck in the middle of this debate — lawyers and judges — also had mixed views on the old Three Strikes regime.
The former law could, and did, create anomalous situations where someone with three minor — but nonetheless deemed strike-worthy — offences could find themselves obliged to serve the full term of sentence for their third offence, even though it might not be as egregious as the rapists and murderers that the legislation was meant to keep off the streets.
Many judges, with such cases before them, sought to avoid imposing a third strike through the avenue which the original Act allowed, if doing so would create a manifest injustice.
Unsurprisingly this sparked fiery debate about just what "manifest injustice" actually meant, and inspired accusations of judges being "soft on crims" or even actively trying to stymie the intent of the Three Strikes regime.
For these, and other reasons, Labour repealed the Three Strikes legislation — although it had to wait for its coalition agreement with New Zealand First to end before it could take that step.
However, it will soon be back: Prime Minister Christopher Luxon was adamant on that at his Monday press conference, and at his side associate justice minister Nicole McKee was positively evangelical on the subject.
"Everyone in New Zealand has the right to feel safe in their homes, businesses and communities," she said, and no-one would argue with that.
Lessons have been learned: the bar for an offence to be strike-worthy will be higher, and some greater discretion will be allowed to judges to avoid harsh outcomes and outlier cases.
However, whether Three Strikes is going to achieve what Ms McKee desires remains questionable.
There is much research to suggest that Three Strikes regimes do not work, and that the threat of a lengthy prison sentence for a third strike offence is no disincentive whatsoever to a determined criminal. Indeed, it may even be a perverse incentive to commit a worse crime on the "I’ve got nothing to lose" basis.
But there is also a strong argument that it is too early to fully understand the impact of a strike system.
If, as Ms McKee said, the intention is to keep serious violent and sexual offenders behind bars, many of those worst category of offenders were serving long sentences for appalling crimes at the strike one and two stage, so it still remained to be seen if they would be detained at the Crown’s pleasure for a third time — with a commensurate improvement in public safety and reduction in crime.
That has always been the weakest aspect of Three Strikes: it relies on a post hoc argument that if you do one thing (lock people up) that something else will happen (improved community safety and less violence).
Yes, its proponents may be right, but at the same time that is a gross oversimplification of the complexities of what drives crime and causes criminals to act.
Truly addressing the wellspring of undesirable behaviour is a much harder task than simply locking people up and throwing away the key.
The proposed legislation will need to work hand-in-hand with another piece of Act New Zealand legislation, Queenstown list MP Todd Stephenson’s member’s Bill requiring all rehabilitation programmes to be completed for parole eligibility.
But even before that stage a greater emphasis on crime prevention is required.
Three Strikes is the hearse at the bottom of an awful cliff, and it would be better for all if it were never needed in the first place.
