Detectives yesterday accessed the messages after being alerted that they had been put on the website.
John Dundon, 29, and his brother Ger 22, directed comments at Christy Keane, 48, who was released last February after seven and a half years in jail for a drugs offence. He is linked to the Keane-Collopy gang.
His brother Kieran was murdered in 2003 by the McCarthy-Dundons.
A well-placed legal source said it is highly unlikely gardaí will take action arising out of the messages as it would be very hard to bring a prosecution on the basis that the messages constituted threats.
John Dundon, who left Limerick shortly after the murder of rugby player, Shane Geoghegan, is seen on the website stating: “Christy, If you’re looking for me, I’m somewhere in Europe, but I know where you are.”
Ger Dundon then says: “See you soon, mother f***er.”
John Dundon was released from jail last July after serving four and a half years for threatening to kill a state witness at the trial of five men convicted of the murder of Kieran Keane.
Ger Dundon, who had left Limerick, has since returned to the city and has been seen in recent days in Ballinacurra Weston where he lives.
As Christy Keane left prison, his son Liam, 24, was just starting a 10-year sentence after he was found carrying a loaded Glock handgun following a high-speed chase involving armed members of the Emergency Response Unit.