KEY POINTS:
Police investigating the disappearance of Olivia Hope and Ben Smart had doubts about the reliability of their key piece of physical evidence against Scott Watson, according to internal documents.
Major questions are now being raised over two hairs apparently found on a blanket from Watson's yacht Blade - and which were presented to the court as belonging to Olivia Hope.
In a signed affidavit early in the murder investigation, inquiry head Detective Inspector Rob Pope said police believed Watson had murdered the missing pair for a number of reasons but police needed more evidence before he could be charged.
"DNA analysis undertaken by scientists contracted by the New Zealand Police have determined that there is a 1:28,000 probability that one hair fibre located on a blanket in a forward cabin of the Blade as being identical to a sample of Olivia Hope's hair," Pope wrote in May, 1998.
"The scientific analyses of the hair fibre referred to in this application has [sic] not been finally validated in such a manner it may be relied on at this stage to commence a criminal prosecution of Scott Watson for the murders of Olivia Smart and Ben Hope."
The police affidavit, obtained by Watson's father Chris under the Official Information Act, was one of several asking the High Court in Wellington for permission to place listening devices on, or "bug", the telephones, home and yacht of Watson. Police were seeking more evidence against their suspect.
Despite testing of the hairs in Australia and the United Kingdom, police did not get the final validation they were seeking.
In fact, the hair matched to Olivia in New Zealand had a "mixed profile" when it was tested in the UK. "These results could be explained by a contribution of DNA from the hair shaft and an external contribution of DNA in the sample. These results were deemed unsuitable for interpretation," ESR said in a statement to the Herald on Sunday last week. In effect, this hair sample was contaminated.
The English lab found the second hair, which could not be tested in New Zealand, could have come from Olivia or her sister - who was also at the Furneaux party - or anyone, male or female, from the same maternal line.
This form of mitachondrial DNA testing cannot identify a specific individual.
Despite the results and police not getting the validity they were seeking, both of the hairs were presented in court.
Furthermore, and despite the comments of Pope in the affidavit, Watson was arrested before the hairs were sent away for further testing in England, anyway. Police national headquarters declined the Herald on Sunday's request for an interview with Pope, now the deputy commissioner.
In the past, Pope has conceded it would have been difficult to bring a case against Watson without the blonde hairs.
Among those who have voiced growing doubts over the conviction of Watson are a juror, two key police witnesses and a former detective on the investigation.
MPs Rodney Hide and Nandor Tanczos have also called for an inquiry. Olivia Hope's father Gerald also now has serious doubts over Watson's double-murder conviction.
Watson's lawyer Greg King is preparing an appeal to the Governor-General to be filed next year.
