Culture Minister Caral Ni Chuilin paid her partner's brother thousands of pounds of taxpayers' cash for decorating her office - but repeatedly failed to declare the relationship in Stormont's register of interests.
Sunday Life can reveal that since 2009, the Sinn Fein heavyweight has handed over £11,320 from her office cost expenditure budget to John 'JJ' Magee to decorate her north Belfast office.
Following Sunday Life's revelation, Sinn Fein last night issued a statement saying the minister's failure to declare the family link was an "administrative oversight".
Magee, a joiner by trade who is also a serving Sinn Fein councillor, also received more than £55,000 of taxpayers' cash from other Sinn Fein MLAs for similar work.
He is the brother of Mrs Ni Chuilin's common-law husband Gerard Magee, a Sinn Fein press officer.
But she repeatedly failed to declare this on the Assembly's Register of Interests which state that any relationship by "blood, marriage, or partnership equivalent to marriage" has to be noted.
Section 12 of the register states: "In this section Members should register any family members who benefit directly or indirectly in any way from Office Cost Expenditure."
Her Sinn Fein colleague Fra McCann for example declared on the register than he employed a niece of party colleagues Paul and Alex Maskey as his PA.
However, Culture Minister Caral Ni Chuilin answered "none" on several occasions when asked to list family members who benefit directly or indirectly in any way from her office cost expenditure.
In response to Sunday Life's questions about her failure to say her partner's brother benefited from her office expenditure, Sinn Fein said last night: "This was an administration oversight and one that will be rectified.
"The party has declared publicly that a range of necessary maintenance and refurbishment work on Teach Carney and other Sinn Féin offices has been carried out by JJ Magee and by his construction company over many years.
"The work carried out was to a high standard and represented good value for money and has facilitated Sinn Féin in providing first-class accessible constituency services."
A Sunday Life investigation into JJ Magee's Assembly business contracts show that not only was he paid £11,320 by Caral Ni Chuilin, he pocketed a total of £68,000 of public funds from Sinn Fein over five years.
When we attempted to question the Belfast city councillor about this he told us to "ring the press office" before hanging up the phone.
For the past five years building firm boss JJ Magee has been Sinn Fein's go-to man when it needs construction jobs done at its offices across Belfast.
In 2011 he unsuccessfully stood for election to the Assembly as a Sinn Fein candidate in north Belfast.
But despite failing to make it to Stormont a busy Magee still reaped £68,000 of public funds paid to him by the party.
Sinn Fein's first recorded payment to the joiner-turned politician was in 2009.
That was when Caral Ni Chuilin, who is effectively his sister-in-law, coughed up £5,080 for decorating work at her Antrim Road office.
In 2011 five Sinn Fein MLAs - Paul Maskey, Jennifer McCann, Sue Ramsey, Pat Sheehan and Paul Butler - paid JJ Magee a total of £27,775 for renovations and maintenance.
He was raking it in again during 2012, receiving £15,750 from Gerry Kelly (left), Caral Ni Chuilin, Jennifer McCann and Sue Ramsey for painting and cleaning.
In 2013 Gerry Kelly, Caral Ni Chuilin, Fra McCann, Jennifer McCann, Sue Ramsey and Pat Sheehan paid Magee £11,176 for similar work.
So far this year he has pocketed a further £8,153 from Fra McCann, Rosie McCorley, Pat Sheehan and Sue Ramsey for painting and electrical work.
All of the 31 registered Assembly payments to Magee, which cover five years, were made in the five week period between March 27 and May 1.
Since 2009 he has received £16,560 solely for work carried out at Sinn Fein's north Belfast office at 291 Antrim Road. The two-storey town house is used by both Caral Ni Chuilin and Gerry Kelly.
Sunday Life's revelations about Caral Ni Chuilin's failure to declare she was employing a family member to do work, is the latest expenses controversy to engulf Sinn Fein of late.
Last month BBC's Spotlight programme revealed that the party had paid a research company run by its own finance managers, called Research Services Ireland (RSI), £700,000 of public funds.
One Sinn Féin MLA was reported to have said they had never heard of the company until they saw it on their annual expenses.
It further emerged that Sinn Fein was claiming thousands of pounds in office rent costs on buildings owned by three different cultural societies to which the party has strong links.