The Special Criminal Court has found Wayne Dundon and Nathan Killeen guilty of the murder of Limerick businessman Roy Collins in the city five years ago.
Mr Collins died after being shot in the chest at the Coin Castle Amusements Arcade on 9 April, 2009.
Dundon, 35, of Lenihan Avenue and Killeen, 23, from Hyde Road, both in Limerick, had pleaded not guilty to his murder.
Both men have been given the mandatory life sentence.
The Special Criminal Court, presided over by Ms Justice Iseult O'Malley, delivered its verdict today, two weeks after the two-month trial ended.
The prosecution claimed that Dundon directed the murder from prison, Killeen was the getaway driver and another man, James Dillon, was the gunman.
They said the motive was vengeance for a ten-year prison sentence Dundon blamed on the Collins family, who had given evidence against him in a previous trial.
Much of the State's case was built on the testimony of five witnesses; two McCarthy brothers - cousins of Wayne Dundon - and three members of the Collins-Keogh family, whom the court heard knew both accused well.
The court dismissed the evidence of Gareth Collins as not reaching the required standard. However, it accepted some of the evidence of his sister Lisa as corroborative.
It also found the forensic evidence, gunshot residue on Killeen's clothing, as compelling and convicted him of murder.
It also found Dundon guilty of the murder on the evidence of convicted murderer Anthony 'Noddy' McCarthy, evidence that was corroborated by the testimony of a prison officer.
The court found no evidence that his testifying would improve his prospects of release.
The defence, however, characterised them as gang associates and supergrass witnesses whose evidence could not be relied on.
Roy Colllins' family hugged and cried after the verdict was delivered.
Steve Collins this afternoon read a victim impact statement to the court.
Breaking down in tears several times, he said his son Roy was an innocent man and a good, upstanding decent member of society.
He said he was a loving, caring and attentive son, brother, father, partner, nephew and grandson.
Mr Collins said: "On 9 April, cowardly evil men devoid of any standards of mercy or humanity murdered him, shooting him in an act of cold blood. And why? Because we did our civic duty as a family.
"Since these people infected our lives with their hateful poison, every moment of every hour since that awful day we are numb with grief. Our sense of loss so profound impossible to find words to describe.
"It is a loss we will never get over. There are days when it is difficult to do basic tasks."
Mr Collins said the family had also been handed a life sentence and he said "all this happened because we stood up to these people".
Mr Collins also spoke about how the family had been forced to leave Ireland and said the family will never get over the loss of their son.
He described how he held his dying son in his arms: "He was gasping for breath and he wanted me to know he loved me and his mother.
"When they murdered my son they wounded me and I am slowly bleeding to death. I live with the reality that they came for me."
Speaking about the impact of the killing on his wife, Mr Collins said: "No mother should have to bury her child, particularly one whose life was ended by such a callous event."
He added that the victim's brothers and sisters had their "world torn apart".
"The murder cost them the happiest years of their lives. These thugs forced them into a life of fear, always looking over their shoulder."
Mr Collins also thanked the people of Limerick and the public for their support.
He said he hoped the breaking up of the gang and new laws "would be part of Roy's legacy and his needless death would not be entirely in vain".
Speaking outside the court, Mr Collins said the family's ten-year nightmare is over, justice has been served and maybe now they can get on with their lives.
"It's been a dreadful time", he said.
He also said he would like to think the family could return to Limerick and rebuild their lives there.
"This is where our lives and families are", he said.
Mr Collins said he always believed this day would come and he was surprised convicted criminals testified against the two men.
He said: "Sometimes you don't have a choice but to face down criminal gangs; you have to do it and trust the gardaí and the justice system. This is the way to sort this out."