Wellington, Nov 29 NZPA - The Ministry of Justice has appointed a top lawyer to re-interview some key witnesses in the case of Ben Smart and Olivia Hope.

Mr Smart and Miss Hope disappeared in the Marlborough Sounds on New Year's Day, 1998. Yachtsman Scott Watson was found guilty of their murders, but has always maintained his innocence.

The bodies of the missing pair have never been found.

Today the Herald on Sunday reported the ministry had hired Kirsty McDonald QC to review Watson's latest legal move, and she had identified key areas of "potentially fresh evidence".

Watson, who has lost earlier appeals including a plea to the Privy Council in 2003, has applied to the Governor-General for a Royal Prerogative of Mercy.

The application has three possible outcomes -- denial, a full pardon, or a hearing in the Court of Appeal.

Watson's application is being investigated by the ministry which will advise Justice Minister Simon Power of its findings which he will pass to Governor-General Sir Anand Satyanand for the final declaration.

Ms McDonald is carrying out legal analysis and inquiry work. The newspaper said that a letter from Mr Power to Watson said Ms McDonald had reviewed the application and found possible evidence unavailable at the time of the trial.