January 2014: A Garda sergeant based in Mullingar was coming to national prominence as a whistleblower within the force. His allegations of the quashing of penalty points were being investigated by the powerful Public Accounts Committee.

Sergeant Maurice McCabe's name was not well known at that point. However, he was about to become publicly associated as a Garda whistleblower over the course of the next few turbulent months.

During that time, the head of the gardaí retired in disputed circumstances, followed by the departure of the top civil servant in the Department of Justice. Next, the Minister resigned as a welter of justice issues dominated political discourse.

In all, it was a time when the An Garda Síochána was under huge pressure. An internal report on penalty points had failed to quell the controversy. The Comptroller & Auditor General revisited the issue - partly motivated by a confidential disclosure made by Sgt McCabe directly to its office. This led to the hearings of the Public Accounts Committee as it analysed the potential financial loss to the State.

On 23 January 2014, then Garda Commissioner Martin Callinan gave evidence to the committee where he defended the force and denigrated Sgt McCabe's actions as "disgusting".

This is the backdrop to the next section of the Disclosures Tribunal's hearings as it examines allegations that behind the scenes, senior gardaí were smearing the whistleblower to politicians, journalists and others.

Martin Callinan's comments unleashed a political storm and there also followed a public spat between him and members of the PAC, as he strongly argued against the Committee hearing evidence from a serving Garda.

The Committee persisted and on 30 January 2014, Sgt McCabe attended the committee and gave evidence. But in an unusual break with procedure, his questioning was held in private.

Central to the Tribunal's next hearings is what's alleged to have happened around this time.

Most of those allegations are directed at the former head of the gardaí, Martin Callinan, and all are disputed.

First up tomorrow is Fianna Fáil TD John McGuinness, who was chairman of the PAC at that time. The day after Mr Callinan's appearance, the pair met in a hotel car park. The tribunal has already heard that Mr Callinan delayed a press conference in Dundalk to drive to Dublin to meet the TD before returning to Louth.

Mr McGuinness will tell the inquiry that Mr Callinan told him Sgt McCabe abused his own children and his nieces. He has supplied a note he took of the conversation. Mr Callinan acknowledges they spoke about Sgt McCabe but he denies the comments attributed to him.

Another witness whose evidence is keenly anticipated is Comptroller & Auditor General Seamus McCarthy. His interaction with Mr Callinan took place just before that PAC meeting began, although what was said is also disputed.

Two other members of PAC at the time will also be questioned: Fine Gael TD John Deasy, who has previously said he was warned about Sgt McCabe by "a senior Garda"; and Housing Minister Eoghan Murphy.

The full list is available online.