Tax investigator accused of snooping on Roberta Williams' files

The action is part of the Australian Tax Office's continuing purge of alleged rogue investigators.

But its internal investigations - soon to include a fresh probe by corruption buster Tony Fitzgerald, QC, - have been labelled unaccountable and a witch-hunt by the tax investigators' union.

The Tax Office's internal affairs department has also been accused by a whistleblower of inappropriately accessing the bank records of another Tax Office employee.

The senior tax investigator under scrutiny for the illegal tax file check was called to a meeting at ATO headquarters in Melbourne last month about his alleged misconduct.

He was accused of illegally searching and disclosing the tax records of Roberta Williams, a convicted drug dealer and former wife of underworld boss and murderer Carl Williams.

The investigator is facing disciplinary charges as well as potential criminal charges for the alleged illegal search. It is understood the investigator has claimed he searched and disclosed Ms Williams' information after advice from the Office of Public Prosecutions.

The investigator is one of a group of officers from the Tax Office's serious non-compliance unit - which investigates high-level tax offences - which has been under investigation for more than 18 months.

It is believed up to eight officers from the Melbourne-based unit have been interviewed by Tax Office internal investigators. Several have since taken redundancies. The probe began in early 2007 after complaints were made about the relationship between now-former Tax Office senior investigator Peter Spence and underworld identity Mick Gatto.

Last year The Age reported that Melbourne tax investigators were also under investigation over the unauthorised accessing of the tax records of murdered male prostitute Shane Chartres-Abbott.

Chartres-Abbott's records, including his address, were checked on the Tax Office database eight weeks before he was shot outside his house in a 2003 gangland killing.

The Tax Office probe into the checking of his tax file has been unable to determine whether there is a connection between the check and his murder.

Since 2007, a police taskforce has been examining the alleged connection between a suspended policeman and the hitman who murdered Chartres-Abbott. The taskforce has also been unable to determine why the Chartres-Abbott tax file check was conducted.

Australian Services Union tax branch secretary Jeff Lapidos said the Tax Office investigator under scrutiny for checking Ms Williams' file had insisted his actions were part of a co-operation arrangement between the Tax Office and police.

Mr Lapidos also called on the Tax Office's commissioner, Michael D'Ascenzo, to respond to a complaint lodged in July last year involving allegedly improper conduct by Tax Office internal investigators.

He said a Tax Office whistleblower had claimed the investigators had illegally obtained his bank records.

Mr Lapidos also criticised the Tax Office for failing to release the first report by Mr Fitzgerald, saying staff and the public had a right to know its contents. A Tax Office briefing paper says the report should not be released because the "public and private interests of confidentiality and privacy outweigh the public interests of openness and transparency in this particular case".