The illegal spying which earned Kim Dotcom an apology from former Prime Minister Sir John Key went on two months longer than previously admitted, according to a High Court judgment.
The revelation - if accurate - would open a can of worms over sworn admissions the GCSB has made in the High Court and the Court of Appeal over assistance given to police ahead of the FBI-inspired 2012 raid which saw Dotcom and three others arrested.
It could also raise the possibility of a fresh apology to Dotcom because Key's apology was in the context of spying from December 16, 2011 through to January 20, 2012.
Questions have been asked of Prime Minister Bill English but he has not responded. A spokesman for GCSB Minister Chris Finlayson referred questions to the GCSB, even though previous issues around the illegal spying have been handled at ministerial level.
The dates provided in the judgment from Justice Gilbert - released yesterday - extended the range of the spying operation.
Justice Gilbert stated the GCSB had "has admitted unlawfully intercepting private communications of Kim and Mona Dotcom (the Dotcoms) and Bram van der Kolk during the period from 16 December 2011 to 22 March 2012".
The judgment came as part of Dotcom's case against the GCSB for damages and ruled out his ability to access the raw intelligence data harvested by the spy agency through its links to the United States' National Security Agency.
The spying was unlawful because Dotcom and Van der Kolk - also arrested as part of the takedown of Dotcom's Megaupload website - were New Zealand residents. The law at the time made it illegal for the GCSB to spy on New Zealand residents and citizens.
Dotcom's lawyer Ron Mansfield would not comment on the change in dates, beyond saying he was aware of it and was studying earlier evidence and statements from the GCSB.
Dotcom texted comment, saying: "I don't know what to say any more. Speechless. It's sad for New Zealand what this Government keeps getting away with. Time and time again. No moral compass."
That would include an affidavit from an unnamed GCSB staff member in September 2012, who was called to testify in the Court of Appeal after it emerged the help had been sought on the Megaupload case by the police's Organised and Financial Crime Agency.
The GCSB staff member's affidavit stated: "Interception operations were conducted between 16 December 2011 and 20 January 2012 and information of relevance to the Ofcanz request was passed to Ofcanz staff."
The GCSB has already been forced to acknowledge the January 20, 2012 end date was not accurate and that surveillance ran for another 10 days. In that admission - in April 2013 - the bureau explained that the interception equipment was effectively automated and could not be stopped.
If accurate, Justice Gilbert's statement that the GCSB admitted intercepting until March 22, 2012 raises a slew of questions.
It would mean the unlawful spying carried on after the GCSB knew that it was illegal. Internal checks after Dotcom was arrested raised a question about him being a New Zealand resident.
The GCSB testimony from the unnamed staff member said the discovery was made on February 22, 2012 - a month before the new date the spying was said to have ended.
A spokesman for the GCSB said: "As Mr Dotcom has indicated he will appeal Justice Gilbert's decision it is not appropriate for GCSB to make any comment at this time."
It would also raise questions about the information passed to police. Evidence has previously been produced claiming the GCSB provided police nine "Information Reports" between December 20, 2011 and January 20, 2013.
And there would be questions about what Key was told and how that shaped the apology he offered Dotcom.
There are also questions for the office of the Inspector-General of Intelligence and Security.
The previous Inspector-General investigated the unlawful spying and ruled there was "confusion" over what residency meant and how it applied to the GCSB's law at the time.
If the spying continued a month after the GCSB knew it had broken the law, it would likely compel a fresh investigation.
A spokesman for the current Inspector-General Cheryl Gwyn said she would not comment at this stage.
There has never been any evidence made public showing information harvested by the GCSB after January 20, 2012 or whether any information was provided to police after that date.
The extradition process and linked court cases which stemmed from the January 2012 raid have tested the system and found it wanting repeatedly - although Dotcom and his three co-defendants are still bound for the United States.
The district court ruled they were eligible for extradition and that finding was upheld by the High Court. That ruling has been challenged.