Fairfax Media understands that Deborah Beale, Mr Shorten's first wife and the daughter of a former Liberal MP, has been asked by the royal commission about some of her share dealings when she was married to Mr Shorten.
The targeting of the ex-wife of a national political leader by a $61 million royal commission will add weight to Labor claims that the inquiry is part of a "political witch-hunt"
It comes as one of the elders of the labour movement, Bill Kelty, offered a strong defence of Mr Shorten's record as a unionist.
To date the commission's focus on Mr Shorten - at least publicly - has been limited to industrial and political issues from his time as AWU leader.
Inquiries about Ms Beale's finances take the commission's investigation into the personal realm, a development that has angered senior Labor and union figures who know about it.
Fairfax Media is aware that the probe of Ms Beale's finances has been discussed at senior levels in the labour movement.
Mr Shorten is under intense pressure over his time as leader of the AWU. Over the past 10 days a Fairfax Media investigation has revealed deals including employers paying union dues and unexplained cash payments to the union, including from the builders of a major Melbourne road project.
In response to questions about its interest in Ms Beale, a royal commission spokesman said all of the commission's inquiries "relate to matters within its terms of reference".
"However, the commission does not comment on whether or not specific lines of inquiry are being pursued."
Ms Beale comes from a wealthy Liberal family. Her father, Julian, was a federal parliamentarian for 12 years until 1996.
He was close to the late billionaire and cardboard tycoon Richard Pratt, an AWU employer and friend of Mr Shorten. The then AWU leader used Mr Pratt's private jet to travel to represent workers after the 2006 Beaconsfield mine disaster in Tasmania.
Mr Shorten and Ms Beale met while studying for their MBAs.They separated in 2008, after which Mr Shorten married Chloe Bryce, the daughter of former governor-general, Quentin Bryce.
The royal commission has also investigated close friends and associates of Mr Shorten, including his successor at the Australian Workers Union, Cesar Melhem.
The Fairfax Media reports revealed the AWU received $38,228 from builder Winslow Constructors in 2005 for the union dues of 105 workers while Mr Shorten ran the union. Another report detailed nearly $300,000 being paid to the AWU from Thiess John Holland, the joint-venture builder of the $2.5 billion EastLink tollway in Melbourne's east.
The workplace deal struck by Mr Shorten saved the builder as much as $100 million under an agreement allowing the builder to effectively work around the clock and by cutting conditions around rostering, weekend work and working in hot and wet conditions.
Fairfax Media understands that Thiess John Holland at the time regarded the payments to the union as an acknowledgment of the flexibility of the deal.
Neither John Holland nor the owners of Thiess have commented on what the payments were for. Nor has the current AWU Victorian branch.
On Friday former ACTU secretary Bill Kelty offered a strong defence of Mr Shorten and the deal.
"This was the 1990s, the 2000s, the country needed a dramatic increase in productivity and the way people were remunerated ... Bill was a union worker who was brave and negotiated a lot of agreements and underpinning them was a need to increase productivity and real earnings," he said.
"The test is did he do the right thing by the union, and what the union stands for, their members. I like him and I don't apologise for liking him."
Mr Kelty added that Mr Shorten had to expect scrutiny of his record as a unionist. "If Bill Shorten wants to be prime minister of this country, he should not quibble about a major newspaper being prepared to look at what he did when he was secretary of the AWU."
While some of Mr Shorten's federal parliamentary colleagues have offered robust support of their leader, senior union officials contacted by Fairfax Media have failed to offer public support.
Privately, many have condemned the idea of unions taking payments from employers after trading away conditions
Canberra Times 22 June 2015
Bill Shorten another criminal in office, responsible for defrauding the taxpayer, BUT as usual the 'brethren' step in and NOTHING will happen.
Forget about 'tax dodgers' or 'dole bludgers' MP's are Australia's bugbear?