The Abbeylara inquiry has heard how John Carthy's doctor was surprised to find Mr Carthy had a gun on the eve of his fatal shooting by armed gardaí in 2000.
Mr Carthy (27) was shot by the Garda Emergency Response Unit (ERU) on April 20th, 2000, outside his house following an overnight stand-off with gardaí. He was carrying a shotgun.
In its first public sitting in Dublin today, the tribunal investigating the incident heard evidence from Dr Patrick Cullen, the GP who treated Mr Carthy prior to his death.
Dr Cullen told the tribunal he was unaware that the gardaí had restored Mr Carthy's gun to him. They had taken the licensed weapon from him in 1998 because they feared he was unstable.
However, the weapon was returned to Mr Carthy after a psychiatrist from St Patrick's Hospital, Dublin, who was treating him for depression at the time, certified he was fit to hold a firearm.
Dr Cullen, who had treated Mr Carthy on and off for more than 12 years, had not been informed of this. Hesaid he was never made aware of a commitment given by the psychiatrist that he would give the gardaí in Granard notification if there was any change in Mr Carthy's medical condition.
He said the first time he had seen a letter sent to the gardaí by the psychiatrist was when the tribunal provided him with it. Dr Cullen told the inquiry he was taken aback when informed that Mr Carthy had a gun and that he immediately feared he might do himself harm.
He said he arrived at the Carthy home on April 19th in the hope that he might be able to help appease Mr Carthy, who had thrown his mother out the house and fired off a number of shots.
Dr Cullen told the inquiry how he had treated Mr Carthy for manic depression for a number of years. He said Mr Carthy had been frequently come to him in an "agitated state" and had been hospitalised on a number of occasions.
He said he did not think Mr Carthy was an aggressive person but that he suffered from an acute bi-polar disorder.
Dr Cullen told the tribunal that he was aware Mr Carthy had a "heightened animosity" towards the gardaí following an alleged assault in 1998.
Mr Carthy claimed gardaí in Granard, Co Longford, had wrongfully detained him and assaulted him while in custody.
The inquiry continues this afternoon.