Wishart was assigned by the TV3 network to report on the case, and came into possession of some confidential business transaction papers that became popularly known as "The Winebox documents" because they had first turned up in an old wine carton.
Although Winston Peters and other financial journalists and newspapers also had copies of the Winebox documents, it was Wishart who first identified the key "Magnum" and "JIF" transactions,[4] later confirmed by the Privy Council and the New Zealand Court of Appeal to be prima facie criminal fraud.
[6] Wishart continued working on the project as a special investigation for TVNZ, to be carried out in secret with the assistance of Frontline journalist Michael Wilson and producers Carol Hirschfeld and Mark Champion.
A senior Inland Revenue Department investigator, Tony Loo, subsequently told the Commission of Inquiry that he and other IRD staff did not understand how the transactions had worked until they watched Wishart's documentary on TV.
Part of Wishart's first book, The Paradise Conspiracy, was loosely reworked as a feature film, Spooked, starring Cliff Curtis and directed by Geoff Murphy.
[9] After leaving TVNZ, Wishart covered the Winebox enquiry for the National Business Review, the Waikato Times, the Evening Post, the Christchurch Press and other daily newspapers.
[23] Five of Wishart's books—The Paradise Conspiracy, Lawyers, Guns & Money, The Paradise Conspiracy II, Absolute Power and Air Con—have achieved number one bestseller status on the NZ Booksellers national "Bestsellers" list, while several more-Daylight Robbery, The Vintage Winebox Guide, Ben & Olivia, Eve's Bite and Arthur Allan Thomas-reached No.2 on the list.
In November 2009 Wishart became involved in the "Climategate" controversy when he obtained confirmation that leaked emails from the University of East Anglia's Climatic Research Unit were genuine, after reaching CRU's Phil Jones by phone.