Police officers involved in fatal shootings have been allowed to view evidence before being questioned by detectives conducting homicide inquiries into the killings.
Police say they have now changed this policy but the Independent Police Conduct Authority says it was only stopped last year because they threatened to stop cooperating with homicide inquiries if officers were briefed before being interviewed.
The head of the the IPCA and the Police Commissioner are at odds over whether officers should receive special treatment in homicide inquiries following police shootings.
Farah Hancock and Guyon Espiner have been investigating as part of RNZ's investigative series License to Kill.
Here's Guyon Espiner.
