Detectives in charge of case against Scott Watson adamant they got the right guy. But his father vows to get him out of prison, despite new cancer battle.
The only regret for the senior detectives who locked up Scott Watson is that the bodies of Ben Smart and Olivia Hope were never returned to their families.
Rob Pope and John Rae, respectively first and second-in-charge of Operation Tam, remain steadfast in their belief that Watson murdered the young friends on New Year's Day 1998.
To mark the 20 years since Ben and Olivia disappeared, the Herald has launched Chasing Ghosts: Murder in the Sounds - a three-part podcast, feature story and video series - to examine one of New Zealand's most enduring mysteries.
Nothing has changed the minds of the senior police officers about Watson's guilt, although Pope - who went on to become the deputy police commissioner - diplomatically acknowledges high-profile cases will always attract criticism.
"To be quite frank I wouldn't have it any other way," says Pope. "It's one of the great values living in a democratic country like New Zealand and having a judicial system which is sound, fair and transparent."
Rae, who retired several years ago, is more blunt.
"There are a few champions for the cause of Scott Watson for which I have no time. In actual fact, I have no doubt in my mind that he is guilty.
They dismiss the "tunnel vision" criticism of the investigation to say there were 119 suspects - only Watson could not be eliminated.
And the report of Kristy McDonald, QC, which declined Watson's first bid for a royal pardon found most of the issues raised in were not "fresh". They had been raised at the trial where the jury convicted him.
Pope says the 12 jurors sat through 11 weeks of the trial and thousands of pages of evidence.
"That provides the most balanced and fair presentation of what actually the prosecution case was about," says Pope.
"It's very easy to read a book or a series of books that may focus on a particular aspect but a circumstantial case relies on consideration of the totality, not just the elements or snippets of it.
"There is no such thing as a 100 per cent watertight case. If there was I would be looking very suspiciously at that."
But there is regret: the bodies of Ben and Olivia were never found.
"To me that was our biggest failure," Rae says.
Pope: "My whole team would dearly have loved to bring home Ben and Olivia so that John and Mary [the Smarts], Jan and Gerald [the Hopes], could actually properly grieve.
"We all dearly would have loved to have brought finality."