There are 65 unsolved murders in New Zealand.
Given there are about 70 murders a year, that's not a bad track record for police.
But some unsolved murders we know more than others.
Most of us know names like Kirsty Bentley, the Bain family, Scott Guy, Olive Walker and Mona Blades. We have grown up hearing their stories and wondering who is to blame.
A new television documentary called Cold Case has shed new light on the Mona Blades mystery, indicating police, at the time, put too much weight on certain evidence which could have prevented them from catching the killer or killers.
The documentary, which screened on Sunday, is quite astonishing and could, hopefully, give the family the much-deserved closure they need.
However, the reality is this case is now 43 years old. And while solving a case this old would be incredible, the killer or killers might not even be alive.
How much time and resources should go into this cold case when there are other, more recent, cases where finding the killer or killers could be more beneficial for everyone's safety.
In Saturday's Rotorua Daily Post, we revealed Rotorua is home to several unsolved murders and missing people cases.
Among those was Israel Jack, an innocent 20-year-old who was murdered just under five years ago as he walked to where he was staying after a night out in Rotorua.
His body was found at 4.25am on August 18, 2013, on Te Ngae Rd. He had been run over by two different cars - but they weren't the killers.
For the first time his father, Rendall Jack, has publicly said he believed a gang was responsible for his son's death just minutes before his body was run over.
Police, also for the first time, have confirmed that's "probably" the case.
Police have said this case is solvable but the answers lie within Rotorua and people willing to speak up.
I hope the case of Israel Jack doesn't become another cold case mystery we are still trying to figure out in 40 years' time.