Photographs taken at the water charges protest which saw Tanaiste Joan Burton trapped in her car by a mob show that a dissident republican was involved in the chaos.
The images show Thomas Kelly, a convicted gun thug, at the frontline and squaring-up to gardai from the Public Order Unit last Saturday week.
Kelly, who goes by the name of Tomas O Ceallaigh, was previously jailed by the Special Criminal Court for handing a Glock gun and 50 round of ammunition to a prominent INLA member in Dundalk.
The 33-year-old father-of-two was being watched by an undercover surveillance unit when he went to meet killer Eugene Kelly, a veteran INLA man from Dundalk.
Kelly served three years in jail for the crime before returning to live in Tallaght.
Since then he has been involved in the Irish Republican Socialist Party - the political wing of the INLA.
The group is one of the dissident factions trying to muscle-in on otherwise peaceful protests against water charges.
Gardai identified Kelly after trawling through video footage recorded at the Jobstown demonstration in which Minister Burton was trapped in a car and had a water baloon thrown at her.
In a video posted by the Irish Republican Socialist Party, Kelly can be seen confronting gardai who were trying to protect Joan Burton.
Senior gardai have said they are concerned that sinister dissidents had infiltrated water protest marches and blamed them for a spate of attacks on gardai trying to safeguard water meter installation crews.
Gardai have stepped-up security on some members of the Government after Environment Minister Alan Kelly received four death threats, including one that he would have a bullet put in his head.
Gardai believe that along with the INLA and Continuity IRA, activists associated with the Real IRA factions once led by Alan Ryan, who was murdered in September 2012, have also hijacked protests on the northside of Dublin.
Separately, investigations in Limerick have found 'Tiny' Joe Lynch, who appeared in court last week charged with terorism offences, attended a recent anti-water charges rally in the city.
He is the father of Continuity IRA killer Rose Lynch.