48-year-old Bernard Dempsey has been convicted of the murder of James Curran in the Green Lizard Pub in Dublin in April 2005.
Dempsey walked into the Francis St pub and fired three shots into Mr Curran's head as he enjoyed a drink with friends.
He made no attempt to disguise himself. After the shooting he then waved the gun in the air, saying look at this and casually walked out.
The trial in the Central Criminal Court heard that their had been widescale intimidation of witnesses.
Two men were arrested for suspected plotting to interfere with the jury.
Gardaí were at the scene within minutes, but witnesses had left. When they were contacted most said they had been in the toilet when the shooting happened.
Some admitted being in fear of their lives.
The key witness in the case, Bernard Kinsella, had threats made to his life.
The prosecution went to the High Court to have him taken into custody to protect him before he gave evidence, and he himself went as far as the Supreme Court to try to stop the Court calling him as a witness.
But in the end he gave a clear and unequivocal account of what happened. His bravery was acknowledged today by the trial Judge.
Mr Justice Paul Carney said he had tried three separate murder cases where someone undisguised walks into a pub and fires a bullet into someone's head in the presence of a substantial number of people whom he knows.
'These are people who have come to think they are invincible and can do this sort of act with impunity', he continued.
He said that due to a number of people two of three of these invincibles are now serving life sentences.
