New Zealand's only maximum security prison is once again being criticised over the availabilty of potential weapons to inmates.
Convicted murderer George Baker took another inmate hostage at Auckland Prison at Paremoremo on Thursday, armed with a makeshift knife.
Baker, 27, is serving a life sentence for strangling 17-year-old Liam Ashley to death in a prison van in 2006.
The prison says Baker barricaded himself and an elderly prisoner inside the facility's special needs unit about 3pm on Thursday.
He gave himself up at 1.45am on Friday after negotiations with prison officers and police and is undergoing a psychiatric assessment.
The Corrections Department says Baker had been demanding a transfer to a less secure unit and has now been isolated at the prison.
The department says it seems Baker was able to fashion a knife out of items found in the prison's recreation room. He used a similar weapon to attack a Corrections officer in July last year.
Northern regional manager Warren Cummins says Baker is known as a dangerous and erratic prisoner, but it is not clear what triggered the hostage-taking.
Prison not adequately staffed - union
A union representing prison officers, the Corrections Association, says the jail has been warned many times that inmates have a frightening array of potential weapons at their disposal.
Corrections Association president Beven Hanlon says the prison is in a state of disrepair, with bits of metal sticking out of walls which can be broken off and sharpened up as a weapon.
He says the prison is not prepared to pay the maintenance to fix it up.
Mr Hanlon believes the situation could have been avoided if the prison had been adequately staffed.
"If you just look at recent history: we've had a prisoner murdered, a prisoner taken hostage, two staff stabbed and nine or ten other prisoners stabbed, as well as numerous beatings that have hospitalised prison officers and prisoners."
Corrections Minister Judith Collins says security will be increased at Auckland Prison if the police investigation shows it is necessary.
Ms Collins says the Government has already instituted measures to improve safety, including stopping prisoners being able to store razor blades in their cells.
String of convictions
Baker also has a numbers of other convictions, including the home invasion robbery of an elderly woman, threatening to kill, aggravated robbery and serious assault.
In July 2008, Baker attacked a prison officer with a weapon as he was being taken back to prison from hospital.
Baker's lawyer Tony Bouchier said he is usually a model prisoner and may not have been taking his medication.
Mr Bouchier says the prison is not a mental health institution and cannot offer Baker the care and treatment he needs.
The president of the Howard League for Penal Reform, Peter Williams, agrees, describing the jail's special needs unit as very poor.
He says it is about time the Government established a more appropriate facility for the criminally insane.
Detectives are investigating the latest incident and inquiry is expected to take several weeks.