Cops and swabbers who solve crime star in new forensic true-life show.

New Zealanders are about to see for the first time how police solved the grisly murder of Carmen Thomas. A new TV show will take a look at the forensic marvels used to crack high-profile murder cases that shocked the nation.

Thomas' dismembered body was found inside containers of concrete buried in the Waitakere Ranges in West Auckland in 2010.

Her ex-partner, Brad Callaghan, was sentenced to life in prison in 2012 for murdering her by repeatedly hitting her on the head with a baseball bat when told he was not the father of their son.

He was also sentenced to six years for perverting the course of justice.


Callaghan had claimed he had been in regular contact with her by text after she had gone missing.

Thomas' family this week declined to comment on the case being played out again as part of five-episode documentary series Forensics NZ. The CSI-style show examines ground-breaking detection techniques used to catch killers, including blood-spatter patterns, DNA, toxicology, entomology and the latest scientific technology.

In an episode to be screened next month titled Operation Keppel it is revealed how blood-spatter analysis on Thomas' washing machine proved the force and the impact of the weapon.

Forensic testing was also done on the plastic of a wheelie bin missing from Thomas' flat and which was found at Callaghan's house with the serial number gouged out. It was believed this was used to transport her body and the testing enabled the serial number to be revealed and subsequently confirmed which address the bin belonged to.

Forensics NZ presenter Simon Morton believes the series will reveal scientists as the real heroes of modern-day crime-fighting.

"I'm not sure scientists get the profile they deserve because they tend to be people who are fairly humble and they are doers rather than talkers," he said.

"In this series you start to understand the role that science has in civil society in terms of keeping criminals accountable. Viewers will have a new level of respect for people who work in this area. It is a peek into a previously unseen world."

In the episode examining the Thomas case, it is revealed how linguistics experts analysed the text language of the victim's and the offender's phones that demonstrated the differences between the two and proved the texts sent from Thomas' phone after she had gone missing were actually written by Callaghan.

Phone polling also proved both the victim's and the offender's phones were always in close proximity to one another from the time of Thomas' disappearance.

It is also revealed how document analysis was done on hand-written notes and envelopes to determine who wrote the notes.

Episode one highlights the case of murdered Auckland taxi driver Hiren Mohini.

Zhen Xio, 24, fled to China after he stabbed Mohini to death in his taxi in the Auckland suburb of Mt Eden in January 2010.

He was arrested and tried in China - the first time in New Zealand criminal history a person had been tried in another country for a murder committed in this country.

Xio was given a 15-year sentence for murder by a panel of three trial judges in Shanghai.

Forensic NZ shows how the killer would have escaped justice if it wasn't for a clever combination of forensic techniques.

"We have looked at these cases with integrity and have not included too much gore," Morton said. "We have also gone out of our way not to be too cheesy or hammy like some of the American true-crime shows can be.

"People are intrigued by real crime partly because it could happen to them or someone they know.

"It is good to know there are dedicated and talented people in New Zealand who are doing their best to make sure these criminals are brought to justice."

Forensics NZ premieres on Prime at 8.30pm next Sunday, April 24.