TIMOTHY Cairns was the special adviser (Spad) to former DUP enterprise minister Jonathan Bell.
He was Spad to Mr Bell throughout the Strangford MLA's time as enterprise minister from May 2015 to May 2016.
For some months before this, Mr Cairns had been a special adviser in the first minister's office during Peter Robinson's tenure.
After graduating from Ulster University in law and government, Mr Cairns had several stints since 2002 working in the DUP as a policy officer and ministerial adviser.
He is not currently employed by the DUP, but in January last year, he was appointed by the party to the board of cross-border business body InterTradeIreland.
He is also the director for Northern Ireland of the Community Transport Association.
Mr Bell alleged that Mr Cairns told him that other DUP Spads were not allowing the RHI scheme to be closed in September 2015.
The former MLA also said he believed Mr Cairns saw himself as working for the other Spads and not him as minister.
But Mr Cairns has accused Mr Bell of bullying, swinging a punch at him and trying to break his finger – claims Mr Bell denies.
Read more:The other key figures at the RHI inquiry
