Q Radio News / PA
Arlene Foster's said with hindsight she wishes she had sacked Jonathan Bell as Enterprise Minister when she could have, but there was an upcoming election to think about.
Mr Bell was in charge of the Department responsible for the RHI Scheme when costs started spiralling out of control.
The Former Minister's previously told a public inquiry the DUP is trying to pin the blame on him.
But, its Leader says there's no "narrative" to discredit him, and had it been her decision she'd never have given him the job.
Meanwhile, Mrs. Foster said late deputy first minister Martin McGuinness knew about a warning from a whistleblower about the scheme.
Controls to limit the scheme's costs were not introduced and overly generous subsidies saw the taxpayer bill spike dramatically.
Questions over the Democratic Unionists' handling of the overspending RHI scheme led to the collapse of political power sharing at Stormont early last year.
Mr McGuinness resigned as deputy First Minister in January 2017 in protest at the handling of the RHI scheme.
Mrs Foster told the inquiry he knew about the contents of the note which she received in January 2016.
She said the note was the first time she heard of the potential for fraud in the scheme, although the then head of the civil service Malcolm McKibbin had raised concerns with her over the financing of the scheme.
Mrs Foster said she had passed the note to Mr McKibbin.
"I knew that once I handed it to the head of the civil service, that it was being dealt with in the appropriate way," she told the inquiry.
A senior Sinn Fein worker Aidan McAteer has claimed in his written evidence to the inquiry the note "was not shared" with Mr McGuinness "at that time".
Mrs Foster queried that during her evidence to the inquiry on Tuesday, and said if she did not give it to Mr McGuinness, she spoke to him about it.
"My recollection is clear, if I didn't show it to the dfm (deputy First Minister), I certainly spoke to the DFM about it," she told the inquiry. "
And in any event the head of the civil service works for both myself and the deputy First minister, so I presume that the minute that was sent to Andrew McCormick... if it came into the DUP system, it would have went into the Sinn Fein system, so I would have imagined that Sinn Fein were aware of that document."