An ex-special adviser to former Northern Ireland first minister Arlene Foster has resigned from his role at Stormont.
Dr Andrew Crawford has denied attempting to keep a botched green energy scheme open.
He was named by a senior civil servant during an explosive hearing at Stormont as the person who exerted pressure to keep the Renewable Heat Incentive scheme running when officials wanted to close it.
It has ended up costing taxpayers a predicted £490 million over the next 20 years and precipitated the collapse of powersharing at Stormont.
Dr Crawford had been most recently a special adviser with the Department of Agriculture.
Mrs Foster said she accepted his resignation with regret, describing him as a "faithful servant" to the party and the people of Northern Ireland.
"Andrew has felt that given what occurred yesterday and indeed today that he was becoming a distraction to the important work of his minister, but indeed he was becoming the story," she said.
"Anyone who knows Andrew Crawford knows he's a very private person and he didn't want to become the story.
"I have accepted his resignation regretfully I have to say."
The resignation was announced minutes after Sinn Fein Finance Minister Mairtin O Muilleoir ordered a public inquiry into the RHI.
Mr O Muilleoir said there was a need to "get to the truth".
The RHI furore precipitated the collapse of Stormont powersharing.
Mr O Muilleoir said: "This inquiry will be impartial and objective. I will not interfere in its work. It will be tasked to get to the truth of this issue."
Last week DUP leader Mrs Foster called for a public inquiry. She had written to Sinn Fein this week in relation to the establishment of a probe.
In recent weeks Sinn Fein had insisted a public inquiry would have been too time consuming.
Mrs Foster welcomed Mr O Muilleoir's announcement.
"We wanted to say we very much welcome the change of heart from Sinn Fein in setting up this public inquiry," she said.
"It is something I have been wanting for some considerable time."
She added: "Earlier this week I wrote to the other parties, and indeed Sinn Fein, suggesting a way forward and now I am very pleased the inquiry is going to be set up and finally we will get some due process in around these matters and we will get the truth in relation to what happened with the Renewable Heat Incentive scheme."
Mr Crawford's brother is a poultry farmer who is a recipient of payments under the RHI scheme.
The senior party adviser, from Beragh in Co Tyrone, has always denied wrongdoing.
At a hearing of the Assembly's Public Account's Committee on Wednesday, a senior civil servant from the Department of the Economy, Dr Andrew McCormick, said he believed, through hearsay, that influence was being exerted by Mr Crawford to keep the scheme running at a high tariff level.
The state-funded RHI was supposed to offer a proportion of the cost businesses had to pay to run eco-friendly boilers, but the subsidy tariffs were set too high and without a cap, so it ended up paying out significantly more than the price of fuel.
This enabled applicants to "burn to earn", getting free heat and making a profit as they did so.
Claims of widespread abuse include a farmer allegedly set to pocket around £1 million in the next two decades for heating an empty shed.
Confirming his resignation, Mr Crawford said: "In light of the allegations made at the Public Accounts Committee yesterday, I believe it is appropriate that I step back from my position in government and resign as a special advisor.
"I am conscious I have become the focus of the story.
"I want to see a full and independent inquiry set up immediately so that it will become clear that at all times I acted with complete integrity in all that I did. I will be happy to give a full account of all of my actions during this period to the inquiry and for due process to take its course.
"However, at this crucial time for Northern Ireland it is vital that I do not become a distraction from the real choice which faces the people of Northern Ireland.
"The election on 2nd March will be the most crucial in the recent history of Northern Ireland.
"At stake is the future direction of Northern Ireland and whether people want a future in which the DUP continues to hold a strong position or one where republicans dictate the political debate with insatiable demands."
"I will continue to offer my full support to the party and intend to campaign for the election of the strongest DUP representation in the next Assembly.
"I do not intend to make any further public comment on these issues prior to an inquiry."