Police handling of conflicts of interest and the execution of search warrants are criticised in a report released by the Independent Police Conduct Authority yesterday.
It comes after a complaint by Dunedin man Bruce Van Essen, whose home was searched by police in September 2006 for suspected ACC fraud.
The authority has criticised the way the case was handled and the search was carried out.
The police officer who sought the search warrant from Dunedin District Court, Constable Andrew Henderson, relied on information provided by ACC private investigator Peter Gibbons - his father-in-law.
Authority chairwoman Justice Lowell Goddard said Mr Henderson either should not have been put in the position of dealing with his father-in-law or his work should have been properly supervised.
"Police did not properly manage an apparent conflict of interest in this case. Nor did the search warrant application meet an acceptable professional standard," said Justice Goddard.
While the authority found no evidence of illegality or misconduct on the part of police, the risk with any apparent conflict of interest undermined public trust and confidence in the police, she said.
The authority found that police management in Dunedin knew of the relationship between Mr Henderson and Mr Gibbons and should have more actively managed the case to avoid any perception of conflict of interest.
Justice Goddard also criticised the way in which the search warrant was executed. It lacked any clear description of offences Mr Van Essen was supposed to have committed and provided no documentary evidence of any offence, she said.
During the search of Mr Van Essen's home, there was a discrepancy between a police record and a job sheet over how many computer memory sticks were taken.
Mr Van Essen alleged that one of the memory sticks was stolen, and made a theft complaint.
Police interviewed all those involved in the search, and found there was no evidence of theft andthat only two memory sticks were taken.
The Independent Police Conduct Authority found the theft complaint was properly investigated, but the investigation should have "frankly addressed the discrepancy between the record of items seized and the job sheets".
It highlighted the care that needed to be taken in recording exhibits.
The authority has recommended tightening policies on police conduct of searchers and on conflicts of interest.
Police said they would review processes that related to conflicts of interest and search warrants.
Acting southern district commander Detective Superintendent Malcolm Burgess said the report found that the police could have done better "in managing perceived conflicts of interest and in the way we obtained and executed search warrants".
While police would certainly review their processes in light of the report, they already had much clearer guidelines to follow in both areas, Mr Burgess said. "Our code of conduct adopted in early 2008 addresses issues around conflict of interest, as does the Auditor-General's 2007 guidelines on managing conflicts of interest in public entities."
Mr Burgess said that external agencies' requests for police to complete applications to obtain search warrants were also under review.