RHI players whose witness statements have just been divulged - Arlene Foster, Richard Bullick, Conor Murphy, Stephen Harron, David Gordon and Ciaran O’Connor
DUP leader Arlene Foster headed up the Department of Enterprise, Trade and Investment (Deti) between 2008 and 2015.
The Renewable Heat Incentive (RHI) scheme was designed under her leadership in 2012.
The Fermanagh and South Tyrone MLA previously served as Environment Minister and went on to serve as Finance Minister before succeeding Peter Robinson as First Minister in 2016.
In December of the same year she was accused by her party colleague and Deti successor Jonathan Bell of failing to introduce crucial cost controls in the RHI scheme.
The former Strangford MLA has claimed Mrs Foster overruled him and kept the scheme open when cost issues became apparent.
Richard Bullick worked for the DUP from 2000 until he quit in early 2017. He was subsequently appointed head of public affairs at MCE Public Relations.
He served as the party's head of policy from 2002 to 2007 when devolution had been suspended and was a key figure in negotiations which led to the restoration of Stormont.
The former barrister was appointed special adviser to Peter Robinson in 2008 and also served under Mrs Foster when she took over in January 2016. He was paid a £92,000 salary. Former DUP Spad Dr Andrew Crawford previously told the inquiry that he shared a confidential legal letter with Peter Robinson's lobbyist son at the request of either the then First Minister or Mr Bullick.
The Sinn Fein MLA was first elected to represent Newry and Armagh in 1998.
He resigned in 2011 but replaced Mickey Brady in 2015 and was re-elected in 2017.
The former Regional Development Minister has served on numerous committees during his time at Stormont. Crucially he sat on the Enterprise, Trade and Investment committee between 2015 and 2017 as the deputy chairperson.
Mr Murphy claims he only became aware of incentive problems following the release of an Audit Office report into RHI in July 2016 but was aware the Deputy First Minister wanted the scheme closed from February of the same year.
Mr Harron worked as a salesman for Hegan Biomass Ltd between 2015 and 2016.
In this role he met with clients of the Dungannon-based renewable heating firm in addition to clients he had sourced himself.
His job was to assist them with the purchase and installation of biomass boilers and renewable energy products.
Mr Harron purchased two boilers himself in February 2016 and contacted Mrs Foster seeking a delay to the closure of the scheme.
He says the boilers he installed in commercial units have not been accredited and that he never received payment under the RHI scheme.
The former BBC NI producer turned spin doctor took up a role as NI Executive Press Secretary in October 2016.
His job was to give "well informed" and "strategic" media advice to the First Minister, Deputy First Minister and the Executive. In December 2016 he sent an email to Mr Bullick in which he discussed pre-empting a BBC story by dealing with the "real story" of why cost controls were delayed in 2015.
He was tasked with advising the Executive Office and Department for the Economy in relation to RHI and met with a range of high-profile people over the Christmas holidays, including the head of the Civil Service Sir Malcolm McKibbin and Attorney General John Larkin.
The fomrer landscape gardener was appointed as a Sinn Fein special adviser in 2015.
He was one of four special advisers attached to the former Deputy First Minister Martin McGuinness but also took instructions from Aidan McAteer.
In February 2016 he told a colleague that he forwarded a memo from Jonathan Bell to his party's policy advice group (PAG) but denies any involvement in or understanding of the RHI scheme.
Originally from the village of Oranmore in Co Galway, the Ulster University graduate was also Sinn Fein assistant in the European Parliament before being appointed to the role, which came with a £63,736 salary.