The Dublin-based inquiry was due to publish its findings this month, but publication has been pushed back to September due to the workload.
“There’s no particular reason for the delay. They’re still working away on it,” tribunal spokesman Killian Morgan said yesterday.
Mr Justice Robert Barr heard evidence from 169 witnesses during 208 sittings of the inquiry.
After hearing closing submissions on December 7, the chairman said he hoped to deliver his report to the Oireachtas within six months. This deadline is also cited on the tribunal’s website.
Justice Barr and his staff are believed to be still working their way through evidence transcripts, expert reports and final submissions. The tribunal was established in 2003 to investigate the circumstances surrounding the fatal shooting of Mr Carthy outside his home in Abbeylara, Co Longford, in April 2000.
The 27-year-old, who had manic depression, was shot four times from behind, by two members of the Garda Emergency Response Unit as he walked in the direction of Abbeylara village carrying a shotgun loaded with a single cartridge.
His death followed a 25-hour armed stand-off with gardaí during which Mr Carthy fired several shots from the window of his house.
Justice Barr is due to make his report to the Oireachtas within six months.
Mr Carthy’s sister, Marie, this week criticised the Garda Commissioner for accepting the retirement of Superintendent Joe Shelly, who was criticised in the Morris Tribunal report.
She said it was an “absolute disgrace” that Supt Shelly, who was the scene commander of the Abbeylara operation, could retire on full pension on July 31 even though the Barr tribunal had yet to report.