Controversial right-wing Whale Oil blogger Cameron Slater has given evidence to the spy service watchdog about how he obtained politically damaging information from the SIS.
Mr Slater arrived at Defence House in Wellington in uncharacteristic silence, refusing to speak to media before appearing before the Inspector General of Intelligence and Security.
The spy watchdog is investigating claims made in Nicky Hager's book Dirty Politics which allege the SIS overruled normal Official Information Act request processes and fast-tracked information to Mr Slater.
The blogger and an unknown number of prime ministerial staffers have been summonsed to explain how Mr Slater got politically damaging information about former Labour leader Phil Goff during the 2011 campaign before other media outlets.
They are also being questioned about whether someone in John Key's office helped him.
Mr Key has said he has never handled an Official Information Act request and was out of the country at the time.
Mr Goff gave evidence at the hearing earlier this week.
Cameron Slater is not the only central figure in Dirty Politics coming under scrutiny; his friend and former justice minister Judith Collins got a grilling at a candidates' meeting in the Papakura electorate last night.
A former High Court judge will conduct a Government inquiry into allegations Ms Collins was involved in a smear campaign against former Serious Fraud Office boss Adam Feeley in 2011.
But voters are divided on whether there should be a wider inquiry. Asked in the latest ONE News Colmar Brunton poll if the two current investigations are enough 44% said there should be a wider inquiry while 46% believe two is enough.
Labour leader David Cunliffe says it is not simply a matter of the minister of justice abusing her ministerial powers. "This is creeping corruption across the government, it affects the Prime Ministers Office."
Neither of the inquiries will be completed before the election but Mr Key is rejecting demands by Labour to be consulted on the terms of reference.
The hearing is closed to the public.