Detective Inspector Dave Lynch revealed this week that the person who confronted Mr Cunningham at the property and had the altercation with him that led to the stabbing would not be charged.
"A thorough investigation has been conducted and the file referred to the Auckland Crown Solicitor for review and legal opinion," he said.
"For any criminal charges to be laid, police would need to be satisfied that the property occupier who killed Mr Cunningham was not acting in self-defence.
"After a review of the recommendations from the Auckland Crown Solicitor, police have decided that there is insufficient evidence to proceed with charges."
Mr Lynch said that because of a lack of evidence, the case did not meet the legal requirements for initiating a criminal prosecution.
"Accordingly no charges will be laid. [But] the decision would be reviewed in the future should any new information be received."
Crown Solicitor Simon Moore, QC, said he could not comment on the specifics of the case.
On their website, the New Zealand police offer advice on what a person should and can do if they come across an intruder in their home or on their property.
"Be prepared to physically defend yourself. The most vulnerable parts of an attacker's body are the eyes, nose and genital area," the website states.
"You are allowed to use force against your attacker when defending yourself, but be aware that if you use something as a weapon in self-defence, it could be turned against you."
Mr Cunningham's family were told of the decision before it was made public.
"Understandably they are upset and police sympathise with them," said Mr Lynch.
"Police have notified the coroner of the decision and are unable to comment further on the circumstances surrounding Mr Cunningham's death pending inquest proceedings."
Mr Cunningham had played for the Patumahoe Rugby Club, where his funeral was held.
Defending your home
*Every person is justified in using, in the defence of himself or another, such force as, in the circumstances as he believes them to be, it is reasonable to use.
*There are also circumstances in which a person, and anyone acting lawfully to assist the person and under his authority, is justified in using reasonable force to protect his property. These include resisting having something taken by a trespasser, defending his dwelling from someone breaking in, and preventing trespassing and removing trespassers, but does not permit a person to strike or do bodily harm to the trespasser in the process.
*Self-defence and reasonable force does not provide immunity from prosecution for using self-defence. Unless the circumstances clearly show the force used was appropriate and in self-defence, the person who has used the force may have to explain their justification to a criminal court.
Source: Neighbourhood Support NZ
