BURIED in a Burwood backyard, hidden inside olive oil drums - to deter sniffer dogs - was $85 million belonging to a former assistant tax commissioner, Nick Petroulias. This is what a former prison inmate and alleged informer told investigators who pressed him for evidence about his former jail buddy, Petroulias.

But, in an affidavit tendered in court, the man, known only as Mr G, claims he told officers a ''fanciful story so they could work out for themselves that they are wasting their time [interviewing him]''.

The man, a former professional footballer and convicted fraudster, says investigators wanted dirt on Petroulias, whom he met at Silverwater jail, and asked him to ''go along with the script''.

Over 11 months, he claims he was repeatedly mistreated by guards, interrogated and threatened with more charges by officers from three states, a federal police officer and staff from the Australian Crime Commission.

Later, he claims the tax office cancelled his tax file number and sought to recruit him as a ''special little helper''.