In July 2018, Maguire was drawn into an inquiry (Operation Dasha) by the NSW Independent Commission Against Corruption (ICAC) regarding possible corruption involving the former Canterbury Council, through his association with former councillor Michael Hawatt. It was alleged that Maguire had acted on behalf of a "mega big" Chinese client, asking for help in buying into development-approved projects, in return for a commission from the developer for both himself and Hawatt. As a consequence, Maguire resigned from the Liberal Party, and from his roles Parliamentary Secretary for the Centenary of ANZAC, Counter Terrorism, Corrections and Veterans. After initially refusing to resign from Parliament, he announced he would do so before its next sitting. Maguire tendered his resignation to the Speaker of the Legislative of Assembly on the afternoon of 3 August 2018. At the ensuing by-election held on 3 September, the Liberals lost almost half of their primary vote from 2015, allowing independent Joe McGirr to end the Liberals' 61-year hold on Wagga Wagga.