Former Customs officer Allen Jones does not have an opinion on whether Scott Watson is guilty or innocent of murdering Ben Smart and Olivia Hope on or about January 1, 1998.
But one of one thing he is very sure - the ketch that played such a major role in the investigation, and in some quarters has continued to cloud the validity of Watson's conviction, did not exist.
The case against Watson largely hinged upon him returning to his boat, Blade, with Smart and Hope after celebrating the New Year at Furneaux Lodge, in the Marlborough sounds. The defence claimed that the couple had actually gone aboard a ketch. That was supported by water taxi operator Guy Wallace.
Efforts to identify and find the ketch have failed, and Mr Jones, now living in retirement in Kerikeri, said last week that he knew why.
"There was no ketch," he said. And he had a compelling argument to support that belief.
Mr Jones, who spent the latter part of his career (1994-2005) at Opua, said Customs had established the Coastwatch programme (which he had co-ordinated in the Far North) to identify 'yachts of interest'. He had had two approaches from police, one formal, the other informal, in the course of the inquiry and prior to Watson's appeal, about the ketch.
Fundamental to his view that the ketch did not exist was the reality that mariners were inquisitive. That was the principle that made Coastwatch successful.
"It was about people keeping an eye out to see what was going on," he said.
"It was about putting the word out when something like this happened. And I have never believed that a vessel like the one described could have arrived and left without coming to notice."
As described, the ketch had not conformed with any known designing, meaning it would have been home-built. That in turn meant it would have stood out.
"Some nosey bugger will always be interested in your boat," Mr Jones said.
"And a lot of people were looking for this one, but still it has never been established that it existed."
Various people had claimed that the ketch had "taken off" after Smart and Hope disappeared, but that didn't ring true either. Standard practice for vessels travelling to New Zealand was to give authorities 48 hours' notice of their pending arrival, while any that left the country without following the notification process would be flagged at their next port of call.
All arriving and departing vessels were also photographed, while Mr Jones had been involved in Project Cook, which plotted virtually every recreational vessel in the Pacific by and for US Coastguard, New Zealand and Australian Customs. That had been in operation in 1998.
"If this ketch had left New Zealand we would have known where it went and who was on board," he said.
"I am 99.9 per cent sure that it did not exist.
"I have no opinion about whether Scott Watson is innocent or guilty, but a lot of effort went into looking for the ketch. The anchorage (at Endeavour Inlet) was absolutely chokka. To say that someone could sail a reasonably large boat into that fleet, anchor, then leave and disappear, is silly."