Gresham Marsh was jailed for life' />

A double murderer has threatened to sue his family and a victims support lobby group he claims is "judging" him.

Gresham Marsh was jailed for life after he murdered elderly couple John and Josie Harrisson during a burglary in Te Akau, west of Huntly, in 1994. He was 22 when he shot the couple after they woke during the night-time robbery. His accomplice was Leith Ray.

In a letter to Garth McVicar of the Sensible Sentencing Trust, Marsh expressed his concern for the victims' family. But the prisoner, who is receiving ACC-funding trauma counselling, then claimed his family had lied about abuse he says he suffered as a child. When news broke last year about the funding, his sister questioned his trauma claims.

Marsh's family and the Harrisson family are united in their attempt to keep the killer in prison. In the letter, Marsh blamed the trust for supporting his family.

"You and your trust are not my judges. I have been judged by the law," he said. "I want to make it clear that this letter in no way changes or minimises what I have done to the Harrisson family and the lives I have destroyed. There are some things it is time for me to say."

He added: "Many times I have wanted to speak but have chosen not to because of the pain and suffering caused by my hand to the Harrisson family."

He was writing the letter from Rangipo Prison to say he was taking legal action against all parties.

"The next time you hear from me will be in court," he said. Marsh's lawyer Michael Bott confirmed Marsh was discussing suing his family. Mr Bott is investigating his claims of abuse. "Gresham's letter is more out of the frustration at the continued campaign against him and the fact that he's never had a chance to tell his story," said Mr Bott.

Marsh felt goaded into writing the letter by what he regarded as the campaign of hate he had endured via his family and Sensible Sentencing.

But his sister, Rowene Marsh-Potaka, said: "He can go for it. I'm not fazed at all. Our family know the truth.

"He can bring us to court. He can go for it."

Mr McVicar said Marsh's letter showed a man desperately seeking excuses for what he had done.

Marsh and Ray were denied parole last year but will reappear before the Parole Board in September.