Smithwick Inquiry due to resume in Dublin 1 February 2013 Last updated at 06:36 The Smithwick Inquiry is due to resume in Dublin on Friday. It is investigating claims of garda collusion in the IRA murders of two senior RUC men. Chief Supt Harry Breen and Supt Bob Buchanan were killed in an ambush in south Armagh after leaving a meeting in Dundalk garda station in 1989. Former Ulster Unionist Lord Maginnis is to give evidence and the tribunal will also hear about the health of key witness Owen Corrigan. Last September, the tribunal was told that Mr Corrigan would not be medically fit to give evidence for up to five months. Mr Corrigan, a retired detective garda sergeant, is one of three former Dundalk-based sergeants who have been granted legal representation at the tribunal. All three deny allegations of collusion. The Dublin-based tribunal was established in 2005 and has been hearing evidence in public since June 2011. It had been due to issue its final report in November 2011 but was given an extension to early 2012. The latest extension is to 31 July this year.