No further legal action could be taken against David Bain if a coroner was to find he was responsible for the deaths of five family members, the New Zealand Law Society has said.

A jury at the High Court in Christchurch on Friday found Mr Bain, 37, not guilty of the murders of his parents and three siblings.

Chief coroner Neil MacLean has said the implication of the verdict was that Robin Bain killed his family, then committed suicide and as a result, existing death certificates might be incorrect.

Radio New Zealand reported that Dunedin coroner David Crerar was considering whether to hold inquests into all five deaths.

Law Society spokesman Jonathan Krebs today told Radio New Zealand that if the Coroner were to find Mr Bain had killed his family the double jeopardy rule would prevent further legal action against him.

The New Zealand Bill of Rights states: "No one who has been finally acquitted or convicted of, or pardoned for, an offence shall be tried or punished for it again."

Mr Bain's lawyer Michael Reed, QC, said a coronial inquiry would be a waste of money and could take months.

"How is a coroner ever going to deal with that massive amount of evidence?"

Mr Reed said his legal team hadn't yet looked into the compensation issue for wrongful imprisonment.

Mr Bain had to now prove his innocence, which was a very hard thing to do, he said.

"I think it's absolutely ridiculous. There should be a formula. In these circumstances, like David Bain, when he has been in prison wrongly for 13 years there should be automatic compensation."

Prime Minister John Key said potential compensation would be assessed by Cabinet only if expert advice considered him innocent.

Mr Key said the Bain camp needed to file a claim and that would then go to an independent Queen's Counsel, who would then advise Cabinet about whether he or she considered Mr Bain was innocent.

"If the recommendation was that he was innocent, then there would be a compensation claim worked out through the Cabinet process," he told TV One's Breakfast programme.

Mr Reed has also urged Mr Bain's relatives to give him back an inheritance that, he says, is legally his.

Mr Bain's family owned a house in Every St, Dunedin, which was burned down just weeks after his parents and three siblings were shot dead in June 1994.

The Bains also owned a section in Whangarei and another in Bundaberg, Queensland.

They had about $60,000 invested with friends and a substantial amount in an overseas bank account, the Press reported.

Mr Bain was initially convicted of the five murders and received nothing from the sale of the properties, to prevent him from benefiting from the proceeds of crime.

His lead QC, Michael Reed, says he hasn't heard from the family yet "but I'm hoping they might wish to make that gesture to David - he's got no money after all".