It remains New Zealand's most famous cold case murder, with Christchurch Detective Inspector Greg Murton overseeing an unsolved killing that has had police stumped for nearly a quarter of a century.
In July, he announced the reward offer but Cresswell said that came with a risk because it could encourage someone to "make up something utterly untrue just to get the money''.
She said that could result in a wrongful conviction and "somebody innocent being put in prison".
About 50 pieces of information related to the murder have apparently come forward since the reward was announced but Murton assured they would be thoroughly reviewed.
"That information must go through a rigorous assessment process to determine its validity and whether it requires further investigation,'' said Murton, who in 2014 became the third inspector to lead the case.
"Rewards are offered in certain circumstances, with specific and stringent procedures in place.''
A sizeable cash reward is not a new murder-solving ploy by New Zealand police.
In 2019, $100,000 was also offered for information about the notorious unsolved murder of Christchurch mother Angela Blackmoore.
She was 10 weeks pregnant when she was stabbed 39 times in her home in 1995, while her 2-year-old son Dillon slept in the next room.
A year later, after reward information came forward, an amateur contract killer was jailed for the horrific murder.
Murton admitted the Kirsty reward offer was with one focus in mind.
"Our goal is, and has always been, to find out what happened to Kirsty and provide her loved ones with a sense of closure,'' he said.
Murton also acknowledged the impact the case still clearly had on the wider Ashburton District.
"It's clear to see, after all this time, there remains a high level of care and concern in the Ashburton community for Kirsty and her family,'' he said.
"We again urge anyone in Ashburton with information that may assist to come forward."
Catch Kirsty's killer
What: Police are desperate for help to solve the longstanding murder of Ashburton teenager Kirsty Bentley.
The story: Kirsty's body was found 18 days after she disappeared while walking the family dog in Ashburton on New Year's Eve 1998. It is New Zealand's most famous cold case murder.
If you have information: Contact the police via their 105 non-emergency number and reference Operation Kirsty. Or call Crime Stoppers anonymously on 0800 555 111.
Reward: A $100,000 has been issued and would remain in place for six months. Immunity from prosecution may be considered for any accomplices should they come forward.
- guardianonline.co.nz
