The Cook Islands Public Service Commissioner, Navy Epati, is under investigation by police.
The Prime Minister Henry Puna says Mr Epati will not be suspended while under investigation.
The Police commissioner Maara Tetava says his officers received help from New Zealand police with the investigation, which centres on a fishing company Mr Epati has involvement with.
He says it remains to be seen whether Mr Epati will face criminal charges, and if so when.
Cook Islands news reports that in 2008, Mr Epati worked as an advisor to the Northern Cook Islands Fishing Company on its proposal to the Cook Islands government, despite being the public service commissioner and effectively the employer of the marine resources secretary.
That sparked concerns among senior staff at the Ministry of Marine Resources at the time, although an audit review of the issue found no evidence against Mr Epati.
In early June this year police received a formal complaint against Mr Epati from another government agency, which sparked the investigation.