South Australia's corruption watchdog has vowed to change its processes after a review found "inexcusable" failings in its investigation of a former senior public servant, including infringing a foreign country's sovereignty.
John Hanlon, the former chief of Renewal SA, was in 2020 accused by the state's Independent Commission Against Corruption of fraudulently claiming private travel expenses - including airfares, accommodation and meals - during a trip to Germany.
But the charges against Mr Hanlon were dropped before the case went to trial.
Mr Hanlon has consistently denied any wrongdoing and no findings of guilt have been made against him.
A District Court judge found evidence gathered by ICAC investigators without the permission of German authorities was inadmissible.
"Their failure to do so constituted an infringement of Germany's sovereignty," ICAC Inspector Philip Strickland found in his review.
"The conduct also had the potential to cause diplomatic embarrassment to Australia or South Australia."
ICAC Commissioner Ann Vanstone said the inspector's criticisms were fair and agreed in principle to his recommendations to improve the body's processes, including more staff training and better record-keeping.
Ms Vanstone acknowledged "substantive errors" stemming from inadequate planning of the Germany trip by investigators.
"The failures that came thereafter were serious," she said.
"As a result, a matter that should have been adjudicated at trial has not been, and the commission's reputation has been damaged; both of which are matters of regret."
Ms Vanstone castigated some sections of the media for "perpetuating falsehoods", including that the commission doctored evidence and that complainants in the case were "vexatious underlings".
"This narrative is entirely false and sets a dangerous precedent that undermines and harms whistleblowers," she wrote in a response tabled in parliament on Tuesday.
An ICAC spokesperson declined to specify which members of the media the commissioner was referring to.
Ms Vanstone also noted the inspector found the initial decision to investigate Mr Hanlon was "reasonable and appropriate".
