Perceived sexual rejection and thoughts of revenge are among the reasons why a psychologist believes there is "very high risk" that Scott Watson would commit violent crimes if released from prison.
The Parole Board declined Watson's first bid for freedom last week and today released the written reasons for the decision in which they described him as an "undue risk to the safety of the community".
He is currently serving a life sentence for the murders of Ben Smart and Olivia Hope in the Marlborough Sounds on New Year's Day in 1998 but maintains his innocence.
Watson was assessed by two psychologists this year and is challenging the opinions and content of both. Only the second report in April was taken into consideration by the Parole Board and parts were quoted in its ruling.
"Mr Watson is assessed to present with a very high risk of violent recidivism. His level of insight, ability and motivation to manage his risk factors remain unknown," the psychologist is quoted as saying.