From carbon emissions to a full-blown crisis - how a heating scheme lit a fire under Stormont.
November 2012: An initiative to reduce carbon emissions called the Renewable Heating Incentive (RHI) is announced by the then Enterprise Minister, Arlene Foster. It financially supports businesses, public sector and other non-domestic organisations to meet the cost of more environmentally friendly technologies.
Autumn 2013: A whistleblower contacts Mrs Foster and asks for a meeting to raise concerns. A second message is sent a few days later with more specific concerns. At a meeting with officials, the whistleblower's concerns are not taken seriously.
January 2015: A reappraisal of the scheme due from the Department of Finance is overlooked as a result of a "combination of staff changes and administrative oversight". Meanwhile, applications to the scheme increase.
February: It is claimed RHI will overspend by at least £460m over a 20-year period. Mrs Foster's successor as Enterprise Minister, Jonathan Bell, announces his intention to close the scheme to new applications. An internal investigation gets under way.
July: The Audit Office says "serious systemic failings" in the scheme will cost hundreds of millions of pounds. It reveals a farmer will make £1m just for heating an empty shed. Its report concludes that the fact that there was no cap on subsidy payments meant that the more heat applicants generated, the greater the subsidy they were paid.
October: Stormont's Public Accounts Committee (PAC) call the mishandling of the scheme "one of the biggest scandals" since devolution. Senior members of regulatory body Ofgem E-Serve reveal there were no minutes taken of formal meetings between themselves and departmental officials between August 2014 and November 2015.
November: With the realisation that the funding available for applicants is uncapped, Stormont tightens the rules. But a massive late surge of 900 applications is received before changes can be made. The PAC is told that a £405m hole will have to be plugged over the 20-year lifetime of the scheme.
December: The original whistleblower argues that "five minutes" of research would have shown up the fundamental flaws in RHI.
December 12: Mrs Foster says she won't quit and insists she has "nothing to hide". She reveals the Executive is to write to claimants to seek permission for their names to be made public in a bid to restore public confidence.
January 9 2017: Martin McGuinness announces his resignation in protest at Mrs Foster's refusal to step aside for an investigation, collapsing the Executive.