2014
January 23rd: Assistant Garda commissioner Nóirín O'Sullivan first comes to widespread attention as she is seen sitting, unmoved, beside then Garda commissioner, Martin Callinan, at the Public Accounts Committee (PAC) as he describes the allegations of Garda whistleblowers as "disgusting".
March 25th: Commissioner Martin Callinan steps down "in the best interests" of the force and for "family reasons". O'Sullivan appointed acting Garda commissioner.
November 25th: O'Sullivan appointed Garda Commissioner after open, international competition for the post.
2015
January 29th: O'Sullivan holds major conference with 250 of the most senior Garda officers outlining challenges ahead in her reform agenda, including combating abuses such as the false termination of penalty points.
March 25th: O'Sullivan tells Oireachtas Justice Committee that lessons have been learned from recent scandals and that ongoing reforms will create a "world class" police force.
July 23rd: O'Sullivan defends the appointment of her husband, Det Supt Jim McGowan, to lead a criminal investigation into a Garda officer's alleged involvement in the leaking of a story about two Roma children being removed from their families as they had blonde hair.
2016
April 25th: Retired Judge Kevin O'Higgins submits his report, following his investigation into matters – raised by whistleblower Sgt Maurice McCabe – in the Cavan-Monaghan district. It finds McCabe "performed a genuine public service at considerable personal cost" and "acted out of genuine and legitimate concerns". The report highlights serious flaws in policing in the Cavan-Monaghan division and says a number of victims were "not well-served" by local gardaí.
May 13th: Irish Examiner reports O'Sullivan had instructed Garda legal counsel at the O'Higgins inquiry to attack McCabe's character and question his motivations. Calls for her resignation follow.
September 9th: O'Sullivan, in a public interview at the Kennedy Summer School in New Ross, Co Wexford, says members of An Garda Síochána have "a duty" to speak out if they believe they see wrongdoing in the organisation. She says significant investment is taking place in updating stations and facilities, and that "the only issue left was pay".
October: Thousands of gardaí plan not to report for duty on Friday, November 4th, in a dispute over pay, ignoring the orders of O'Sullivan. Crisis ensues as the government seeks to clarify which Garda services will be in place and contingency plans are made to protect national security. The "strike" is called off at the 11th hour and the government intervenes on pay issue.
November 21st: O'Sullivan confirms reports she broke Garda rules by using a personal gmail account for Garda business.
2017
February 17th: The Government establishes the Tribunal of Investigation into alleged smear campaign against McCabe, to be chaired by Mr Justice Peter Charleton.
February 20th: The Irish Times publishes a report outlining problems with breath test data and the fact that an audit was under way. The Policing Authority was unaware of the audit and is not impressed.
February 24th: Policing Authority chairperson Josephine Feehily questions whether O'Sullivan can carry on as commissioner while Charleton Inquiry underway.
March: A Garda report states that almost one million breath tests logged on Pulse never took place.
March: Interim report on large scale financial irregularities at the Garda training college in Templemore, Co Tipperary, is submitted. Policing Authority is informed of financial mismanagement.
April 11th: O'Sullivan describes "crisis of confidence" in the Garda and tells senior gardaí they "must do better", in an address to the annual conference of the Association of Garda Sergeants and Inspectors.
May 4th: O'Sullivan appears before the PAC to discuss issues at Templemore. She admits internal financial processes are not fit for purpose but insists majority of problems are legacy issues. She is contradicted on aspects of her evidence by John Barrett, the Garda's director of human resources. He said he had a two-hour meeting with her in July 2015 to discuss Templemore issues. She says the meeting was "brief". Calls for her resignation are dismissed by Minister for Justice Frances Fitzgerald.
May 8th: Policing Authority chairwoman Josephine Feehily raises concerns about the veracity of Garda crime statistics.
May 11th: Fresh crisis as it emerges O'Sullivan delayed informing the Minister for Justice of apparent Templemore financial irregularities. Further calls for her resignation.
May 25th: It emerges senior gardaí knew of financial irregularities at Templemore in 2008 and did not inform Garda internal audit unit of these.
May 28th: O'Sullivan's mobile phone which was to provide crucial evidence to Charleton Inquiry, goes missing.
June 14th: O'Sullivan's testimony to the PAC contradicted again. She told the PAC she first became aware of the issues at Templemore on July 27th, 2015 and acted immediately. Cyril Dunne, former administrative office with the Garda, tells PAC he told her about issues in the first week of July 2015.
June 20th: Comptroller and Auditor General criticises O'Sullivan for failing to inform his office of financial irregularities at Templemore.
July 13th: PAC blames O'Sullivan for failing in her duties as accounting officer of the Garda.
July 20th: Policing Authority describes as "unfortunate" that O'Sullivan will miss its next meeting as she is taking a six-week holiday in the US. Taoiseach Leo Varadkar backs her.
September 6th: Internal Garda report shows gardaí exaggerated the number of breath tests conducted, between June 2009 and April 2017, by 1.45 million.
September 10th: O'Sullivan announces she is stepping down from the force at midnight because the "unending cycle" of investigations which she says are absorbing her time when she is trying to "implement the deep cultural and structural reform that is necessary to modernise and reform" the force.
She is yet to appear before the Charleton Inquiry
