There must be thousands of criminals in New Zealand wondering if they're about to get caught through modern science.
The use of DNA in catching offenders has taken off over the past decade, providing police and the justice system with a powerful 21st-century tool to wage war against evil.
The latest technologies allow scientists to match the smallest of samples from crime scenes to the person they belong to, and from saliva taken from people arrested with samples stored in the national database.
There have been several recent cases, including two in the Western Bay.
The Bay of Plenty Times Weekend on April 28 revealed the case of a man caught 10 years after he raped a 17-year-old girl in a Mount Maunganui caravan.
It was a despicable crime. But police predicted they would eventually catch the monster - and they did when they took a saliva sample from him for cannabis offending late last year.
The sample he gave was run through the national DNA database and matched with the evidence he left at the crime scene.
In the time that elapsed between his crime and getting caught, his life had changed. He had a 10-year-old daughter and I wonder if he wondered over the years if he was on borrowed time.
I also wonder what she will think of her father when she is old enough to fully understand what he has done.
The second case, reported in the Bay of Plenty Times this week, involved Newton Craig Lawson, a 37-year-old thief who left a blood smear at the crime scene seven years ago only to be identified when caught disqualified driving in Tauranga.
Another case late last month involved a man who tagged a swastika and spat on a visiting Australian aircraft at Whenuapai Airbase in September 2008. That droplet of spit was enough to nail him when he had to give his DNA when arrested over a domestic incident.
One of the most famous New Zealand cases is Jules Mikus, who murdered 6-year-old Teresa Cormack in Napier in 1987. Advanced DNA technology was used to convict him in 2002.
But it's not just the technology but also the powers police have that makes the difference.
Police can compel anyone charged with certain crimes to provide a DNA sample.
They were given wider powers under a law passed in 2009.
The Criminal Investigations (Bodily Samples) Amendment Bill allows police to take samples from people charged with a range of serious offences and from anyone they intend charging with an imprisonable offence.
These powers were a smart move by our lawmakers, giving police greater flexiblity in catching offenders.
There will always be liberals who object to such powers.
When the law was introduced in 2009, the Green Party objected.
Co-leader Metiria Turei, somewhat bizarrely, complained the bill would bring extraordinary powers to police, who could use "assault" to obtain a bodily sample when there was only an intent to charge.
I cannot understand her thinking.
Law-abiding people have nothing to fear.
Today, the National DNA Databank, which has profiles of individuals and profiles from unsolved crimes, continues to be an awesome weapon.
It has been used since 1996, and today more than 108,000 individual profiles are held.
The ESR scientific agency says the overall success rate in DNA matching in this country is world-leading, with 63 per cent of all unsolved cases loaded to the crime sample databases linked to individuals, and more than 30 per cent linked to another crime.
It is critical New Zealand continues to take advantage of DNA developments.
For repeat criminals, it serves as a warning.
If they commit a crime, and leave some trace at the scene, there is a strong chance it will come back to haunt them one day.