The Smithwick tribunal was set up to look at allegations of Garda collusion in the deaths of two senior RUC officers, chief superintendent Harry Breen and superintendent Bob Buchanan, killed by the Provisional IRA on 20 March 1989.
The former Real IRA leader, who was convicted of directing terrorism and membership of an illegal organisation in 2003, is currently serving a sentence on Portlaoise prison.
The 62 year old Louth native was also sued by families of the Omagh bombing in civil court proceedings, and found responsible for the atrocity, which claimed the lives of 29 people — including a woman who was pregnant with twins — on 15 August 1998.
The 2009 civil case led to a judgement of £1.6 million against McKevitt and three others.
Meanwhile, the Smithwick tribunal adjourned early after a brief statement from the chairman, who had been scheduled to hear evidence from former assistant garda commissioner Kevin Carty.
This is the second no-show by Mr Carty, who previously failed to appear before the inquiry on 2 September. At the time the tribunal was told that Mr Carty was based in Vienna and was working with the UN.
On that occasion, Mr Carty later contacted the tribunal to explain that a notice from the tribunal had been sent to an address in Celbridge which was out of date.
In 1989, then inspector Carty worked with assistant commissioner Ned O’Dea on a report prepared in the days following the deaths of the two RUC officers, which concluded there was no evidence of garda collusion in the ambush which took their lives.
“Assistant commissioner O’Dea’s report is the bedrock of the Garda approach to the issue of alleged collusion,” Mr Smithwick said. “It was an investigation carried out at the request of the government of the time and, as will become apparent, it was incorporated into the report of the subsequent investigation carried out in 2000-2001, the so-called Camon/Kirwan report.”
Mr Smithwick said that in early September Mr Carty informed the tribunal that his current address was in Yerevan, Armenia. And earlier this month, the tribunal booked flights in order to allow him to come to Ireland and give evidence on Friday 25 November.
But on Thursday 24 November, Mr Carty contacted the tribunal by email to say he “was not going to attend on medical advice”.
The former district court president said the email enclosed an “unsigned” letter from a doctor in Vienna, and gave an address for Mr Carty in Poland. The letter said that “by reason of a condition Mr Carty suffered in 2009 she recommended that he avoid stress and in particular two flights in 24 hours.”
Mr Smithwick said that if the only problem Mr Carty faced was taking two flights in 24 hours, that could have been easily fixed.
“I am inevitably left in the position of having to consider whether I should refer Mr Carty’s non-attendance to the High Court,” the chairman said. “I hope that this will not be necessary and that he will make himself available so that I will hear evidence from him shortly.”