The murder of Blessie Gotingco has sparked a call for judges to be able to revisit dangerous offender's sentence at the end of their prison time.
The Sensible Sentencing Trust is calling for such a law change, which while it might breach the Bill of Rights at least one law academic believes it is "worth talking about".
Name suppression lifted yesterday for 28-year-old Tony Douglas Robertson, who raped and murdered Mrs Gotingco in May 2014 just six months after being released on strict conditions after serving his full eight-year sentence for abducting and molesting a five-year-old girl.
SST spokesman Garth McVicar says the Government should change the law so an offender's sentence can be reconsidered once they have reached the end of their jail time.
Robertson was given the benefit of the doubt in his 2005 sentencing but chose not to rehabilitate while in prison, Mr McVicar said.
"Despite that, a judge could not reconsider the decision to give Robertson the benefit of the doubt when he reached the end of his sentence... Robertson had not changed one iota."
Currently, the open-ended sentence of preventive detention is only able to be considered at the time an offender is sentenced, Mr McVicar said.
"As intelligent as most judges are, they do not have a crystal ball."
University of Auckland law expert Bill Hodge says the idea is worth talking about and the discussion is owed to Mrs Gotingco's family.
"It's almost like double jeopardy - 'now we've thought about it again and we are going to give you a longer sentence - tough'," Dr Hodge told NZ Newswire.
That might violate the Bill of Rights but it could be deemed necessary in the "tiny, tiny, tiny" minority of cases, he said.
It could apply to the cases such as Robertson, William Bell and Clayton Weatherston, he said.
"Hopefully we would only be seeing a few of these, but when they happen in it can be pretty ugly and spectacular."