The officer in charge of Wellington's Metropolitan Crime Unit says its investigation into a former Inland Revenue Department employee is not over, despite the man's admission of guilt on a charge of corruption.
Alex Song, 32, appeared in Wellington District Court on Wednesday after the solicitor-general approved the charge under Section 105 of the Crimes Act.
Police say a Chinese business couple made a complaint in July after being pressured for money.
Detective Senior Sergeant Darrin Thomson says police are continuing their inquiries, though he believes it is an isolated case.
Mr Thomson says officers laid a charge of demanding with intent to steal, but that was upgraded to one of corruption after the approval of the solicitor-general.
Mr Thomson says Song, who will be sentenced in October, faces a maximum penalty of seven years in jail.
The tax department says it is investigating all cases in which Song was involved.
Inland Revenue Department commissioner Robert Russell says Song's actions were an exception, and that the organisation's 6000 employees have a strong record of integrity.