Police believe the Korean backpacker who disappeared five years ago was killed at Charleston, 27km south west of Westport, and they know how he died.
However, the officer heading the inquiry, Detective Inspector John Winter, still won't confirm whether they were looking for Jae Hyeon's Kim's body when they spent five days searching near Charleston recently.
"We were looking for any items that we connected with Mr Kim's disappearance," he told a Westport media conference today.
Nor would he reveal the cause of Mr Kim's death or comment on any possible motive.
Police today charged jointly two men with the murder of the 25-year-old economics student. Shannon Brent Flewellen, a 28-year-old fisherman, was arrested at his Nelson home this morning.
He appeared in Nelson District Court this afternoon and was remanded in custody to appear in the Westport District Court on Thursday.
He will be joined there by the second accused, a 31-year-old unemployed former Westport man, who did not appear today.
Mr Winter would not reveal where he was arrested or where he currently lived.
He also declined to comment on whether the accused were connected to the Fourth Reich racist gang, members of which were involved in the 1999 Westport murder of transient gay man, James Bambrough.
Mr Winter also headed that inquiry, which resulted in two arrests for murder.
Mr Winter said Mr Kim probably died between September 29, 2003 - when he made his last eftpos transaction in Westport - and October 22, 2003.
The lack of a body was not a barrier to police laying charges, he said.
"The connection - if any - to those charges and what we were doing at the 4 Mile (at Charleston) will come out in due course."
Other persons were still being sought, and additional charges might be laid.
"These arrests certainly don't mark the end of the inquiry. If I might paraphrase Mr Churchill, `this is not the beginning of the end, but the end of the beginning'."
He would not reveal what led to today's arrests, but said the two anonymous letters received by Westport police had not prompted the breakthrough.
Police would consider further searches, although none were planned at this stage.
"(But) we will do everything in our power to try and reunite the Kim family with the body of their son."
He had confirmed the death of Mr Kim to the Korean consultate, who had advised the family in Pusan.
"They are obviously devastated. Over the years they feared the worst but hoped for the best. But their worst fears have been confirmed."
Mr Kim's brother might travel to New Zealand at a later date, Mr Winter said. His parents did not feel they could make the trip.
Police working on the inquiry would remain in Westport for the rest of the week.
Mr Kim arrived in New Zealand in February 2003 and was reported missing by his family in May 2004, five months after he was supposed to have returned home. A police investigation at the time found nothing.
Asked today whether that investigation was sufficient, Mr Winter said it was difficult to say. Mr Kim was an itinerant, travelling alone, who keep intermittent contact with family and friends.
"At that stage, there weren't fears for his safety and no-one was really sure where he had gone."
Nelson police reopened the investigation into Mr Kim's disappearance in May as part of their routine practice to revisit unsolved missing persons cases.
Initially their inquiry focused on Nelson, where Mr Kim's last known address was Alan's Backpackers. However, they moved to Westport when they discovered he had used his eftpos on September 29, 2003, at a local cafe.