Former Garda press officer Superintendent David Taylor will appear before the Disclosures Tribunal this week.
Supt Taylor will give evidence on Monday, Tuesday and Wednesday in public sittings of the Charleton tribunal at Dublin Castle.
The tribunal is looking at claims by Supt Taylor that he was directed by former garda commissioner Martin Callinan to brief the media negatively on Sgt McCabe. Mr Callinan denies this.
The tribunal has previously heard that Supt Taylor sent “hundreds” of text messages to senior officers and journalists as part of a smear campaign against Sgt McCabe.
Sgt McCabe has told the tribunal that an emotional Supt Taylor told him in a meeting that he had “destroyed” him on the instructions of former Garda commissioner Martin Callinan.
Later in the week former minister for justice Alan Shatter and Mr Callinan will appear before the tribunal.