The police reward scheme to catch killers is studded more with failure than success over the past 10 years.
Police have offered big-money rewards for tipoffs to help solve 26 murders since October 1991.
Eighteen of those cases remain unsolved, the rewards never paid.
Of the cases where there have been murder convictions, police have paid only two rewards.
Police paid $20,000 for information that convicted Teina Pora for his part in the death of South Auckland woman Sandra Burdett, said an officer who worked on the case.
Another $20,000 was paid for information that helped convict former Invercargill fisherman Rex Haig of the murder of Mark Roderique at Jackson's Bay, on the South Island's West Coast, in 1994.
Pora and Haig have unsuccessfully challenged their convictions in the Court of Appeal.
In the past 10 years the police commissioner has approved rewards worth $820,000 for tipoffs or other information to help convict killers. Of that amount:
* $570,000 worth of rewards have not been paid in the 18 unsolved cases.
* Rewards worth $160,000 have not been paid in the five cases that police have solved.
* One claim has been made on a $50,000 reward offer. The case is before the courts.
* Police have paid $40,000 for information that led to convictions in two murder investigations.
Despite the rewards' low success rate, Detective Senior Sergeant Don Lee of the investigation support unit said police were confident the scheme worked.
"It's a valuable tool. Some people need an incentive to come forward and usually money is a fairly good incentive," said Detective Senior Sergeant Lee.
The biggest sum offered to catch a killer is $50,000.
It has been offered 10 times, eight times since August 1997, but has not yet been paid.
Rewards are usually valid for about six months. Only two rewards have been renewed, both without success.
"It can save money in manpower and time just by getting that early injection of information which could put the investigation on the right track," said Detective Senior Sergeant Lee.
But the lure of money was not always enough to get the information police needed to solve a particular crime.
"You could offer $100,000 and still that person would not come forward.
"There could be other underlying reasons as to why the witness is reluctant to give information or become involved or is fearful of their safety."
Of course, people simply might not have the information police want.
Detectives in two unsolved Auckland slayings found big rewards did not put their investigations on the right track.
In late July, Detective Senior Sergeant Mark Franklin said "nothing particularly startling" had emerged after a $50,000 reward was announced that month in the hunt for the killer or killers of 23-year-old Marie Jamieson.
The reward to identify Ms Jamieson's killer is the only one still valid and it expires on January 1, next year.
And the $50,000 reward posted for information about the killer of 29-year-old Japanese tourist Kayo Matsuzawa drew a blank.
"Historically reward notices haven't been successful," said the Matsuzawa investigation spokesman, Detective Senior Sergeant Kevin Baker.
The Jamieson and Matsuzawa cases were long-haul investigations, which were more likely to use rewards to get information that could secure a conviction, said Police Association president Greg O'Connor.
A $50,000 reward notice was posted last November for information about the murder of 25-year-old Auckland man Justin Dyne.
The offer led to Lance Graham describing in court how he helped drag Mr Dyne's body into bush at the Waitakere Ranges after his friend allegedly strangled Mr Dyne to death.
The friend, Tristan Rex Lawson, has been charged with the murder.
Auckland lawyer Marie Dyhrberg questions why someone would need to be given money to do their civic duty and pass on information crucial to a police investigation.
"If they required money to relocate [for their safety] that's a different thing."
Information obtained under the offer of a reward would have to be viewed carefully, she said.
One of her clients, Teina Pora, was enticed by a $20,000 reward into lying about his part in the 1992 rape and murder of Ms Burdett, she said.
But Ms Dyhrberg disputes whether Pora was at Ms Burdett's home the night she died.
"So you have a 17-year-old boy with a two-year-old baby and the opportunity to get cash," Ms Dyhrberg said during Pora's retrial last year.
Pora told police he helped hold the 39-year-old Papatoetoe woman down while two senior Mongrel Mob members raped her and then killed her with a softball bat.
He was convicted of Ms Burdett's murder and is serving a life sentence. Ironically for Pora, other people claimed chunks of the $20,000 booty.
Police later offered him a $50,000 non-public reward to reveal the identity of the person whose semen was found in Ms Burdett.
Scientific testing had proved the semen did not belong to the two Mongrel Mob members Pora named.
It was later found to belong to serial rapist Malcolm Rewa who was convicted in 1998 of raping Ms Burdett.
Ms Dyhrberg said during Pora's retrial: "If he [Pora] knew it was Rewa, you would think he would give that name."
* $50,000: Aucklander Marie Jamieson, murdered about February 10, 2001.
* $50,000: Wellington man Terri Robert King, aka Trevor Raymond Heath, shot on or about April 13, 1999.
* $50,000: Ashburton teenager Kirsty Bentley, disappeared on December 31, 1998. The reward has been offered twice, both times without success.
* $50,000: Japanese tourist Kayo Matsuzawa, murdered in Auckland. Her body was found on September 9, 1998.
* $50,000: Vietnamese woman Nguyen Thi Lien, murdered on May 18, 1998, in Auckland.
* $50,000: Aucklander Claire Hills, murdered on April 28, 1998.
* $50,000: Aucklander Jason Raymond Kearney, last seen on August 17, 1996, and believed murdered.
* $20,000: The body of David John Robinson was found in South Westland on December 28, 1998.
* $20,000: Christchurch man John Thomas Reynolds was found dead on April 28, 1996.
* $20,000: Donovan Patrick Reidy died on October 8, 1995, at Ngaruawahia.
* $20,000: Crimewatch on November 14, 1995, announced $20,000 rewards for information about the murder of Timothy Mark Pridding, at Dunedin, and that of Stuart Te Wano, near Gisborne.
* $20,000: Alexa Joy Cullen was last seen alive at her home in Manaia, near Coromandel, on June 16, 1995.
* $20,000: Auckland transient Betty Marusich was murdered between September 18 and 22, 1995.
* $20,000: The body of Christchurch woman Angela Maree Blackmoore was found on August 17, 1995.
* $20,000: Nelson man Kevin James O'Loughlin was murdered on May 2, 1993. The reward was issued twice, both times without success.
* $20,000: Judith Yorke disappeared from Mt Maunganui on October 22, 1992.
* $20,000: Laverne Deborah Luana Williams disappeared from Tauranga on June 5, 1986.
* $50,000: Auckland man Graham Kirkwood, murdered on May 23, 1997.
* $50,000: Margery Hopegood, murdered at Hamilton in 1992.
* $20,000: Christchurch man Arthur Sandston, found murdered in mid-1992.
* $20,000: New Plymouth woman Nora Emma Sole, murdered in February 1992.
* $20,000: Shane Westrupp, died in mid-1991, near Hawera.
* $20,000: Rex Haig, convicted of murdering Invercargill man Mark Thomas Roderique on February 13, 1994.
* $20,000: Auckland woman Susan Gail Burdett was raped and murdered on March 25, 1992. Teina Pora was convicted of her murder.
* $50,000: Transient Justin Dyne was last seen alive on July 25, 2000. His body was found on September 12 that year.