The inquiry into allegations former Justice Minister Judith Collins tried to undermine former Serious Fraud Office boss Adam Feeley will begin a week before this year's September 20 election.
Prime Minister John Key this morning announced the terms of reference for a Government Inquiry into the matter which cost Ms Collins her portfolios.
Mr Key also said the inquiry would be conducted by former High Court Judge Lester Chisholm.
The Government Inquiry will have "full powers" under the Inquiries Act passed last year.
It will investigate whether:
• There is any evidence Ms Collins acted inconsistently with the conduct expected of a minister by undermining or attempting to undermine Mr Feeley's tenure as director of the Serious Fraud Office
• Ms Collins provided information about Mr Feeley during his tenure as director of the Serious Fraud Office to WhaleOil blogger Cameron Slater or any other party not entitled to it
• Ms Collins inappropriately sought or received information about Mr Feeley from Slater or any other party
It would also identify and report on any other relevant issues.
The inquiry will begin on September 12 and is to report back to Mr Key by November 28.
Mr Key earlier this week said the inquiry was likely to have the power to force Facebook and other internet companies to provide records of communications they held relevant to the matter.
Ms Collins resigned her portfolios last Saturday after a 2011 email from Slater emerged in which Slater referred to her "gunning" for Mr Feeley.