Key Points:

New Zealand authorities hamstrung by a lack of co-operation from American agencies have been unable to solve the mystery of a man's death at the South Pole.

Australian astrophysicist Rodney David Marks, 32, died in May 2000 from acute methanol poisoning while working with 49 others at the Amundsen-Scott South Pole Station operated by the United States National Science Foundation (NSF).

His family do not believe they will ever know how their son was poisoned.

"And I don't think we are going to try to find out any more in regards to how Rodney died. I'd see that as a fruitless exercise," Dr Marks' father, Paul Marks, told the Herald from Australia.

Dr Marks was employed by the Smithsonian Astrophysical Observatory, working on the "Antarctic Submillimetre Telescope and Remote Observatory" project.

Because his body was initially flown back to Christchurch, New Zealand took on the role of trying to find answers.

Coroner Richard McElrea yesterday released his findings on the death of Dr Marks, and highlighted the difficulties police investigators had in getting co-operation and reports from the NSF and American contractor, Raytheon Polar Services.

Mr Marks was disappointed neither organisation had made contact with him since his son's death and did not understand why it was so difficult for the authorities to get information out of them. "For heaven's sake, a man has died in your care. Why wouldn't you help the police?"

Suicide was ruled out in the case of Dr Marks - a man who occasionally drank heavily, but was also described as "brilliant and witty".

It was considered possible Dr Marks, a binge drinker, had accidentally drunk the methanol - a poisonous liquid used as a solvent or fuel, but his father found this "inconceivable".

It was also possible that someone else had a role in his consuming it, for a prank or a more sinister motive.

But Mr McElrea said: "There is no evidence before the coroner's court to support this theory."

At a coroner's hearing into the death in 2006, Detective Senior Sergeant Grant Wormald commented on the struggles police had to get American assistance in their inquiry.

Since 2002, police had tried to obtain a list of all people on the base when Dr Marks died, and had to find it themselves on the internet.

A questionnaire forwarded only after long negotiation to those at the base got few replies.

Police believed a full investigation into the events leading to Dr Marks' death had been carried out by the US agencies involved, but had been unable to get access to it.

"It is impossible to say how far that investigation went or to what end," Mr Wormald told the inquest.

A Raytheon spokesman in Christchurch would not comment to the Herald yesterday, while National Science Foundation spokesman Art Brown referred any questions to NSF staff in Washington DC.