Wellington, March 22 NZPA - Police and the Corrections Department say the Sensible Sentencing Trust should not be allowed more time to prosecute them over the deaths of two young people, killed by known criminals.

Karl Kuchenbecker, 26, was murdered by parolee Graeme Burton during a violent rampage in Lower Hutt in 2007.

Debbie Ashton, 20, was hit head-on by one driven by disqualified speeding driver Jonathon Allan Barclay near Nelson in 2006. Barclay was convicted of drink driving a month beforehand. He was on parole and had been given a new identity under the witness protection programme, which led to him being treated as a first-time offender and not sent back to jail.

The trust and the victims' families say Burton and Barclay should have been in prison when the victims were killed.

Last week the trust and the families dropped their bid to hold individual police officers and public servants accountable for the deaths -- but are still pursuing the organisations they work for, seeking reparation under the Health and Safety in Employment Act.

The Department of Labour did not conduct an investigation into either death or bring prosecutions at the time.

In Wellington District Court today, Robert Lithgow, QC, who is representing New Zealand Police and the Corrections Department, said the people responsible for the deaths had already be prosecuted.

He said the trust had only come up with the idea of the health and safety tack following the prosecution of the Sir Edmund Hillary Outdoor Pursuits Centre, where six students and their teacher from Auckland's Elim Christian College died in flash flooding while on a canyoning trip run by the centre in 2008.

Mr Lithgow said the case was a negotiated guilty plea, which was an "unstable basis" for a judicial decision in the Kuchenbecker and Ashton cases.

He questioned whether a district court could add to the knowledge of the cases, considering the Crown could not be fined or sentenced.

Mr Lithgow said a district court judge did not have the power to grant an extension to the rigid six month period in which parties could to apply for an extension in which to lay a prosecution.

In both cases applications for time frame extensions should have been made before January 2009.

Mr Lithgow said there would be other incidents where the legislation could be tested and that would fall within the time frame rules, and not when the Sensible Sentencing Trust or its lawyers explored ways of making the circumstances fit the Act.

However, the trust's lawyer Nikki Pender told the court the Act mentioned a six month time limit only once, which indicated there was room for flexibility.

The time frame was "unfairly arbitrary" and could lead to unreasonableness, Miss Pender said.

No one in the system had been found accountable for the deaths and there was no drive for change.

"This is safety, this is human lives. The public interest in prosecutions is paramount."

Miss Pender said an extension to the time frame would not open the floodgates for similar applications.

"It's only ever going to apply in situations like this, where it has escaped the attention of the Department of Labour it's a matter it should be investigating."

Judge Ian Mill reserved his decision.

In a Parole Board decision released today Barclay, who is serving five and a half years in connection with Ms Ashton's death, was denied parole.