has raised questions about the rights of witnesses or suspects to refuse to give evidence to police.
But the right to silence is fundamental to our criminal justice system.
Does that mean you have the right to say nothing, no matter what?
Yes. The right to silence is a founding common-law principle, enshrined in the Bill of Rights. You must be told of this right before police question you. What if you know something about a crime? Any person, at any time, in any place has the right to remain silent, whether they know something or not, whether guilty of a crime or not.
Is there any difference between the rights of someone who is a suspect and someone who is a witness?
Can't they just get the family in and force them to talk?
You cannot be detained for questioning unless you have been arrested. If arrested, you can be questioned, but again, you have the right to remain silent and the right to be represented by a lawyer. That also applies if you have been charged with an offence.
What other rights are there?
Privilege against self-incrimination. Anyone, any time, any place, whether arrested or not, has the right to refuse to answer questions that would tend to show them guilty of a criminal offence.
Are there exceptions?
You must answer questions if stopped by police while driving a car, you must answer if asked by the Serious Fraud Office whether you have committed fraud or white collar crime.
Can't an exception be made?
No. Otago law professor Mark Henaghan says that would lead to the state being able to question anyone and demand an answer.
What about charging them with criminal conspiracy or accessory after the fact?
Police must prove the charges. They must have evidence of, say, someone overhearing someone else urging a family member not to talk. If they had that evidence, they could charge someone but the person would still have the right to remain silent.
Is the high profile of this case helping police
Probably not. Auckland University associate law professor Scott Optican says the way police tend to deal with cases such as this is by "doing things quietly", finding out where the "pressure points" are and using their skills to get people to talk.
Wouldn't the pressure help to force the family to come forward?
Professor Henaghan says no. While the pressure on the family is "unbelievable", he says MPs are wading in for political reasons and the family are being treated as pariahs. Publicity is "doing more harm than good".
Is there any danger of a conviction falling over because of media coverage?
Yes, says Professor Henaghan. Confessions obtained by police must be freely obtained. You could argue the high profile of this case is enough that a lawyer could argue any confessional statement made to police was obtained under pressure.