An attacker firebombed a home occupied by the innocent brother of a man targeted in a sting by a so-called 'paedo hunter' organisation.
Major damage was caused to the front of the property in the estate in Drogheda when it was attacked at around 1am yesterday, with windows being smashed in.
An innocent man aged in his 40s was in the house at the time but he escaped uninjured.
The property is also understood to be occupied by the innocent mother of the Co Louth man, who was targeted earlier this week by a vigilante group in a child-grooming sting.
Gardai do not believe the vigilante group was behind the firebomb attack and yesterday they condemned it in an online post.
No arrests have yet been made in the case, which gardai believe is directly linked to an online video of the vigilante group's sting on the brother of the man on Monday.
"What happened in Drogheda shows the dangers of the activities of these vigilante groups - a completely innocent man could have suffered serious injury or worse when the property was attacked," a senior source told the Herald.
Previously, gardai have expressed "major concern" at the activities of vigilante groups who describe themselves as paedophile hunters and pose online as children to track down sexual predators.
Earlier this year, in a Virgin Media documentary, Detective Superintendent Declan Daly said gardai welcomed the public's assistance in preventing and detecting crime but added that this "should be limited to reporting concerns" to gardai.
"When members of the public take on the role of law enforcement, that is not a positive development," he said.
"We take child protection very seriously, and the activities of these groups are a major concern for us.
"It would appear to me that the focus of these groups is on publicity rather than justice- focused and it is activity that I can neither welcome nor encourage."
The vigilante group which targeted the Drogheda man on Monday evening claimed it confronted him at his home address for grooming a young girl online.
"The team had documented evidence that showed the suspect had been engaging in sexual communication with what he believed was a 13-year-old female child (decoy)," it said in a statement.
"During the communication with the child, the suspect had sent the child indecent videos of himself and asked her if she liked them."
The man targeted in the sting was later questioned at Drogheda Garda Station before being released without charge.
Gardai said last night that it was "not clear" if the man would face any charges but a senior source said officers did not condone the activities of vigilante groups.
"The actions by such groups are a cause of concern for An Garda Siochana and for other police services," a garda spokesperson had said previously.
"The activity engaged in and the manner of confrontation between such groups and their targets has the potential for violence and could result in harm to persons present.
"In addition, there are also concerns over the legality of the actions of such groups operating in Ireland.
"Finally, the manner in which such groups operate and how they interact with their chosen targets prior to and during the arranged meeting has the potential to affect future criminal proceedings."
The activities of 'paedo hunter groups' came to prominence in November 2017, when Kieran Creaven (55), a former RTE TV sports producer, was arrested in Leeds after a sting.
He was jailed for 18 months in March last year after being caught grooming a decoy who he thought was a 13-year-old girl by paedophile hunting group 'Predator Exposure' in Yorkshire.
Creaven has since been released and is believed to be living in hiding in Dublin.