Witness: 'No ifs, no buts, no maybes - it exists'

Key Points:

An Auckland couple has broken their silence over the "mystery ketch" on which Ben Smart and Olivia Hope were last seen alive - and say the boat's skipper told them he was at Furneaux Lodge in Marlborough Sounds on New Year's Eve, 1997.

Water-taxi driver Guy Wallace says he dropped Smart and Hope at a ketch the night they disappeared, but police have said no ketch existed, instead saying the pair went aboard Scott Watson's single-masted sloop. Watson was convicted for the murders and is serving a 17-year sentence.

But David and Rachel Arlidge say a boat berthed beside them at Bayswater Marina in Auckland at the time of the murder investigation - and seen by hundreds of boaties around the country - matched the description of the mystery ketch.

Police will meet the Arlidges to take a statement, a move that has astonished long-time Watson campaigner Mike Kalaugher.

Last week, Olivia Hope's father Gerald expressed growing doubts about Watson's conviction and said he would try to free him if convinced of his innocence. Two other key police witnesses - Wallace and Furneaux Lodge bar manager Roz McNeilly - have also retracted their evidence and believe Watson is innocent.

Only vaguely aware of the double murders after months sailing in Australia, the Arlidges were at Bayswater Marina in late February/early March, 1998, just a couple of months after Smart and Hope disappeared.

They noticed a "striking" white ketch - with a blue stripe, round portholes, unusual rope work and no name - moored next to them. However, police had said no such ketch was wanted in connection with the murders.

"We were chatting with the guy, so I jokingly said to him, 'Gosh the police must be interested in your boat with this hoo-ha at Furneaux Lodge'," said David Arlidge. "And unbelievably he said to me, without any hesitation: 'I know, I was there'."

The Arlidges didn't call the police as they thought the case was "done and dusted".

The skipper told them he was planning to do some work on the boat but was gone the next day.

Years later, David Arlidge watched a television documentary about the Sounds murders and saw the artist's impression of the mystery ketch. "I got this awful feeling and the hairs on the back of my neck stood up. So I rang Rachel [who was out of town]."

Without prompting, she replied: "That was the boat wasn't it?"

Both experienced boaties are adamant they saw the mystery ketch.

"It was only then we realised we had seen something that was unusual, given that this boat supposedly doesn't exist," David Arlidge said.

"We know what we saw, it was a dead ringer. I know the difference between a sloop and a ketch. I don't make mistakes about boats. No ifs, no buts, no maybes. It exists."

The Arlidges rang Marlborough Sounds' murder investigator Mike Kalaugher, the parents of Scott Watson, and his lawyer.

David Arlidge said he went into Onehunga police station this week and offered to give a statement. He said his offer was treated "quite seriously" and he was told a statement would be taken within a week.

Police refused a Herald on Sunday request for an interview with Deputy Commissioner Rob Pope, who headed the murder investigation.

Pope has previously said that extensive inquiries were made in the Marlborough Sounds, around New Zealand and internationally, and police were "quite clear there was no identification of a ketch involved with the disappearance of Ben and Olivia".

A police national headquarters spokesman said David Arlidge had contacted them about the ketch and a formal statement would be taken. Police would then decide whether the sighting had any significance.

The Arlidges are adamant the ketch exists and hope that coming forward publicly will prompt other people. "We know what we saw. I'm now utterly convinced that Scott Watson is innocent," David Arlidge said.

Mike Kalaugher, author of The Marlborough Mystery, was amazed the police had agreed to take a statement.

"It's extremely rare for the police to talk to anyone since they pulled Scott Watson's boat from the water." The ketch had been sighted hundreds of times, he said, but not all sightings were accurate, and that deterred the police from following every lead.

When told about the police decision to take a statement, Scott Watson's father Chris said: "That's quite strange. It's a pity it's 10 years too late."