UPDATED 11.10am: Convicted double murderer Scott Watson is believed to pose undue risk to the community and the Parole Board says he's unwilling to reduce that risk.

The board has released its reasons for declining Watson parole on his life sentence for the 1998 murders of Ben Smart and Olivia Hope.

During his time in prison Watson has had four recorded misconducts including severely assaulting a fellow prisoner, knocking them unconscious.

While in Police custody before the murder trial, he assaulted a Police officer, causing wilful damage.

Watson also tested positive for drugs while in prison, in 2001 and 2002.

According to the board, while Watson's behaviour has improved and he is 'working well inside the wire', he still shows a tendency for violence.

It says careful rehabilitation measures must be completed for Watson to reduce his risk.

But Watson does not see it necessary to undertake such programmes, and sees no benefit in attending a Dependency Treatment Unit programme for his past drug and alcohol use.

A psychologist says Watson has a very high risk of future reoffending.

The expert has recommended the best path for addressing Watson's violent propensities would be the Special Treatment Unit Rehabilitation Programme.

But according to the psychologist Watson has declined to consider this option; among his reasons, the fact he maintains his innocence for his murder convictions.

The psychologist says that should Watson be paroled and reoffend, he may display a high level of callousness and go to significant efforts to evade detection of that offending.

When the sentencing judge imposed the 17-year minimum non-parole period on Watson, he said the murders were a random killing with all the hallmarks of the work of a lone psychopath:

"I am not in any position in the absence of relevant reports to determine whether Watson falls into that category.

"If he does then the chances of him being released on parole, ever, are remote."

The Parole Board says Watson, some supporters and journalists have strongly expressed the opinion that he is innocent of his crimes.

But the board is stressing to those parties that it is not able to be involved with issues of guilt.

It's jurisdiction can only deem whether a person no longer poses an undue risk to the safety of the community.

Watson remains convicted of the two murders after a jury trial, one appeal, one refused leave to appeal by the Privy Council and an unsuccessful petition to the Governor General.

If he were to be paroled, Watson could never return to the Marlborough or Nelson provinces.