DETI civil servants working on the RHI scheme met Ms O'Hagan in October 2013 to discuss her concerns about the initiative.

Asked if she'd noticed the reference to "misuse" of the scheme in the email that was sent to her, Mrs Foster says she "may have" wanted to meet her personally.

Image source, RHI Inquiry

Officials advised the minister to decline Ms O'Hagan's request for a meeting.

She "got quite a lot of requests for meetings from members of the public" and on "most occasions" it was civil servants who met with them first before there was an opportunity for a meeting the minister.

Mrs O'Hagan, who runs an energy-efficiency firm, sent an email to DETI's general information address in August 2013, asking for a meeting with the minister to discuss how her product could work alongside the "sustainability" of the RHI scheme.

On the same day, he also sent a broadly similar email to Mrs Foster's constituency address, again asking for a meeting and explaining to the minister that the benefits of the scheme meant "many of our potential customers are no longer interested in becoming more efficient".

A third email - again directly to Mrs Foster and again requesting a meeting - was sent about a week later and outlined that the scheme pays claimants "to use them as much [heat] as they can".

Image source, Getty Images

"In fact the incentive to use more is leading to misuse in some cases."

That email wasn't forwarded to DETI officials - Mrs Foster says that's because she believed Mrs O'Hagan's earlier emails was "being dealt with" and she "was getting a response".

She says she didn't pick up on the reference to "misuse" because she "scanned" the email and believed it was similar to the one she'd received the previous week.

Mrs Foster is asked question about the so-called whistleblower who tried to draw her attention to critical flaws in the RHI scheme as far back as summer 2013.

Janette O'Hagan sent emails to the then enterprise minister and her department and while she met civil servants to discuss her concerns they were never properly followed up.

Mr Scoffield digs into the Northern Ireland Assembly's Hansard record from December 2016 of what was a day of high drama (below).

Mrs Foster told the assembly that she thanked Ms O'Hagan "for all that she did to try to prevent the calamity that we have fallen into".

"She deserves our higher respect and a sincere apology on behalf of my former department, which should not have dismissed her claims with disbelief.

"Had she been listened to... the crisis would've been avoided."

Approval was granted by Stormont's finance department for the RHI scheme until the end of March 2015, after which point it would need to be reapproved - it had been intended that that would dovetail with the planned scheme review.

But as we know now, the review didn't happen and reapproval was never sought - Mr Scoffield says the need for it was "simply lost somehow".

Image source, DFP

Asked why that happened, Mrs Foster says she was never informed about the stipulation and she agrees that is was a significant failure on the part of the department.

She says the scheme "was not monitored" properly.

It was a "failing" for DETI not to carry out a crucial planned review of the RHI scheme in 2014, says Mrs Foster.

A review of the initiative was to take place that year but it never happened, meaning that a vital opportunity to spot the ultimately catastrophic flaws in the initiative was missed.

Image source, Getty Images

The former minister says it was one of the key checks to make sure the scheme was fit for purpose but it wasn't her responsibility to oversee that review - it was an "operational matter" for DETI's energy team to handle.

She "can't say... that it really came into my head" and there was "nothing there to prompt me to think about it either".

Image source, RHI Inquiry

Civil servants "took decision upon themselves" regarding the RHI scheme rather than referring them to Mrs Foster, she says.

She puts that down to "pressure" to try to "move things along" as quickly as possible and adds that she doesn't believe there was any "malicious" intent on the part of officials.

"It would be better to be slower than to not be informed," she says.

The Northern Ireland Assembly's Enterprise Committee was given updates on the RHI scheme's performance and those had to be approved by the minister.

Comparison of submissions for May and October 2014 indicate that performance targets were being met and exceeded six months earlier than expected.

Mrs Foster says that wouldn't have "jumped off the page" as its unlikely she would have retained the figures over that period.

And the matter was never flagged up to her by officials.

Dr Crawford has "learnt his lesson" and has "suffered as a result" of media scrutiny over his actions on the RHI scheme.

He resigned from his role as a DUP ministerial adviser in January last year after a senior civil servant named him as the adviser who exerted influence to keep the scheme open, a claim which Dr Crawford denied.

Image source, RHI Inquiry

But inquiry chair Sir Patrick Coghlin says it's "hardly surprising, given what happened, that the media took an interest in it".

Mrs Foster agrees but adds that "one doesn't expect some of the more outrageous commentary around it".

Dr Crawford told the inquiry last week that he still works as an adviser for the DUP on a part-time basis.

Mr Scoffield suggests that might lead the public to conclude that his actions in sharing internal papers without authorisation "hasn't been viewed as something which is particularly serious" by Mrs Foster or her party.

Image source, PA

The DUP leader explains that Dr Crawford has a "backroom role" conducting Brexit research for the party's MEP Diane Dodds.

She says his action were "disappointing from my point of view" but she doesn't believe they should "bar a person from having part-time research employment forever and a day".

Mrs Foster was "surprised" when she found out that her ministerial adviser had shared government papers about the RHI scheme with his poultry-farmer cousin in 2013 and 2015.

Dr Andrew Crawford told the inquiry this week that he shouldn't have done it.

If she had known about what he'd done, Mrs Foster says she would've referred it to David Sterling, DETI's top civil servant at the time, for an investigation, as well as alerting DUP officers.

Asked if she was aware that he sent government documents with people without authorisation, Mrs Foster says she knows he shared information "with other special advisers".

She says she didn't know that some of Dr Crawford's family members were claimants on the RHI scheme.

Image source, RHI Inquiry

Disappointingly for us, Mrs Foster "doesn't "normally sit and watch the RHI Inquiry".

She was responding to Mr Scoffield's query about whether or not she'd seen evidence from the head of the Northern Ireland Civil Service when he said that his guidance to civil servants is that they "don't say 'no' to a minister".

We'd hoped she was one of our many loyal followers...

Image source, Getty Images

Civil servants should "challenge" ministers if they think something they are asking for "is not right", says Mrs Foster.

Inquiry panellist Dame Una O'Brien tells that the "challenge function is "mutual".

Mrs Foster says that most civil servants she worked with "would say that I did challenge them - hopefully not in an aggressive way".

Mrs Foster says "one wishes I had asked more questions" about the RHI scheme and she admits that it "wasn't a personal priority of mine".

"Doesn't mean I wasn't interested, before somebody writes that tomorrow," she adds.

Image source, RHI Inquiry

Inquiry chair Sir Patrick Coghlin points out that it was a "unique scheme" that didn't exist anywhere else in Europe apart from in Great Britain and wonders whether that should "boost it up in your concerns".

The former DETI minister says she had a "false sense of security" that the scheme was "working" in Great Britain and the same would happen in Northern Ireland.

Back to the matter of cost controls, Mrs Foster says that if there were issues that she should have been made aware of "then they should have been brought up to me".

There was no submission made to her that raise the issue and asking for a decision on it.

Image source, RHI Inquiry

"It's very difficult for me to go rooting about in the department to find out that isn't being brought up to me," she says.

The term "rooting around" is "a good Fermanaghism", she jokes!

There were questions about whether DETI should've had responsibility to deal with energy matters, says Mrs Foster.

She says that a Stormont committee had suggested that there could be a need for a separate department to deal with it in the way there is at Whitehall.

Image source, Getty Images

She says the the Department of the Environment (DoE) had responsibility for climate change targets and a question for the inquiry panel will therefore be whether energy powers at Stormont were "located in the correct place".

"Was there a better home for energy division in DoE? It could've been the case at that time?"

Most of the DETI officials who'd developed the RHI project left the department over a period of six months from the end of 2012.

Inquiry panel member Dr Keith MacLean asks whether Mrs Foster was aware of the departure of these key officials and if she'd thought of checking with the new staff that they were aware of the cost controls issue.

Image source, RHI Inquiry

The former minister says that if she started down that road she'd have had to see that each official was properly briefed every time they were moved.

"Frankly, if I did that that's all I would be engaged in as a minister," she says.

In September 2014, Mrs Foster gave her approval for the domestic RHI scheme to open as soon as possible later that year.

But there were still no cost controls in the non-domestic initiative - they'd been put forward over a year earlier but had been put off by the department to allow it to get the domestic scheme up and running.

With the domestic scheme then rubber stamped at that point, Mrs Foster is asked whether that was then a "fairly clear prompt" to prioritise the cost controls forward and "get on with them".

The former minister says there was no concern from her officials about the lack of cost controls and it "wasn't a live issue" at the time.

"The issue of const control was not at the forefront of the officials and 'cause of everything else that was going on in the department it wasn't at the forefront of my mind either."ll

Image source, RHI Inquiry

Back in the Senate chamber for her final day of evidence for now, Arlene Foster will be taking questions from the inquiry's senior counsel David Scoffield QC.

Want to have a glance through Mrs Foster's written witness statement? You'll find it here on the inquiry's website, external.

Mrs Foster was the minister at Stormont's Department of Enterprise, Trade and Investment (DETI) when it set up the RHI scheme in 2012 and in that role she signed off on the project.

A key question for the RHI Inquiry panel will be whether or not she was aware of key information regarding the scheme when she approved it.

Image source, Pacemaker

When the scale of the scandal emerged in December 2016, there were widespread calls for her to resign to allow an investigation to be carried out into what went wrong.

She refused and has consistently denied any wrongdoing in relation to the scheme.

BBC News NI

Arlene Foster dismissed as "nonsense" a claim by the head of the Northern Ireland Civil Service that notes of ministerial meetings were not taken due to concerns about freedom of information requests.

Arlene Foster says she "never" demanded secrecy from officials when she was a minister.

David Sterling had made the claim in evidence to the inquiry last month but Mrs Foster said she didn't accept what he'd said.

The DUP leader said that in all her time as a Stormont minister she had never asked officials not to minute meetings.