THE DUP has declined to comment on the circumstances surrounding former special adviser Stephen Brimstone's application to the Renewable Heat Incentive scheme.
It followed confirmation from First Minister Arlene Foster that he had been a claimant.
The DUP did not respond to requests for comment from The Irish News regarding when and on what basis Mr Brimstone applied to the scheme.
Asked if her former special adviser had been a claimant on the scheme, Mrs Foster told the BBC on Monday: "Yes, as far as I understand Stephen was a claimant."
However, she denied it had any connection to his departure from his role last month, when he left his £92,000 a year post to "pursue opportunities in the private sector."
Mrs Foster said: "Stephen had indicated back in May that he may not be stay for a long period of time and said that he would go off to pursue opportunities in the private sector.
"I do wish him well. Stephen played a key role in the Executive Office...he has decided to move on and he is now a private citizen."
Earlier, the First Minister said she wasn't aware that a brother of DUP special adviser Andrew Crawford, who was her special adviser in the enterprise department, had been a claimant.
On Friday night the party confirmed that Mr Crawford's brother, a poultry farmer, is an RHI claimant but insisted the DUP man does not personally benefit from the scheme.
Mrs Foster said: "I wasn't aware of that because I wasn't privy to who had applied into the scheme."
Stephen Brimstone's next step after Stormont remains unclear, but he is listed as a director for Drewreen Limited in Kesh, Co Fermanagh, with companies house.
The nature of the business, which was set up in 2003, is listed as "buying and selling of own real estate" in records filed with companies house. He was appointed a director in August 2014.
However, apart from an address, there is no listed contact information for Drewreen, with The Irish News unable to find a website, email or phone contact for the business.
Mr Brimstone's brother, Aaron, is the director of Lakeland Karting, which has a separate address on the same road in Kesh.
The 550m outdoor karting track offers racing facilities, a reception area and a conference/meeting room.
It was officially opened in 2012, when then Enterprise Minister Arlene Foster paid a visit and tried out the track in a go-kart.
Asked whether Lakeland Karting had a biomass boiler and was a claimant under the RHI scheme, Aaron Brimstone declined to comment when contacted by The Irish News yesterday.
Aaron Brimstone's wife, Alison, is a former DUP councillor in Kesh, who resigned from Fermanagh District Council in February 2014 citing family commitments and the pressure of her job as a solicitor.
In 2013 Stephen Brimstone became embroiled in controversy when he was accused of telling Jenny Palmer, then the DUP's representative on the Housing Executive board, to change her vote in relation to a contract involving maintenance firm Red Sky, which later went bankrupt.
In its investigation, the Assembly's former social development committee said Mr Brimstone had been "deliberately evasive" in his answers and had failed to provide complete accounts of meetings.
Mr Brimstone denied any wrongdoing and insisted he did not believe he would have used the phrases being attributed to him.
Mr Brimstone did not respond to a request for comment from The Irish News.