The gangland boss had moved to Spain in fear of the new gangs laws, which were supposed to cripple criminal organisations.
Gangster ‘Fat’ Freddie Thompson is back in Dublin.
Detectives were on alert for a violent backlash by the dangerous criminal, who gardai say is pondering his next move.
The gangster – who’s sworn vengeance after his mother’s home was firebombed – was seemingly untroubled by new gangland laws which promised to take him off the streets.
“Up ’til now he was hiding out overseas but now he’s claiming the law can’t touch him. It’s frightening,” said a source.
But former Justice Minister Dermot Ahern's much vaunted legislation appears powerless to curb their activities.
Now that Thompson is back in the city, there's been a huge upsurge in gangland tensions in the Crumlin/Drimnagh area.
Several of his younger associates have been involved in violent attacks.
"He's surrounded by teenage acolytes who have been willing to carry out any act of violence to prove their loyalty. In return Thompson is splashing around cash," said a source.
"It's a very ugly atmosphere and we fear a violent backlash."
'Fat' Freddie spent most of yesterday at his mother's south inner city Marylands home, where he received a number of visitors, and nipped out for some fresh air and a cuppa.
A source explained: "He is absolutely fuming over what happened at the house on Sunday night.
"He wants everyone to know that he is back and he will do everything in his power to defend that property.
"On Wednesday, he was openly walking the streets of Crumlin with some of his young cronies - this is something that he has not done for many years.
"His return has put gardai on high alert - officers just want him out of the city.
"The longer he stays around, the more chance there is that someone is going to be killed."
Among the visitors to Thompson yesterday was first cousin David Byrne (29), from Raleigh Square, Crumlin.
Byrne escaped serious charges after being arrested in relation to a shooting incident near Cherry Orchard Hospital, Ballyfermot, in August 2008.
During the botched hit, a 20-year-old man was shot twice in the stomach. Byrne -- who is said to be "completely loyal" to Thompson -- was arrested by members of the Organised Crime Unit but was only ever prosecuted for the offence of assisting another person to commit an arrestable offence.
Byrne hit the headlines again in 2009 when he was jailed for contempt of court during the first murder trial of 'Fat' Freddie's most bitter rival, 'King Ratt.'
When brought to court to give evidence, Byrne said that he could not remember anything unusual happening on the night of a murder despite giving a statement to gardai at the time.
Mr Justice Barry White asked him: "Do you witness stabbings every day of the week to such an extent that you cannot remember them?"
Byrne said: "Judge, I was on drugs at the time. I've been on drugs the last eight years."
"How many stabbings have you witnessed?" Mr Justice White asked.
"None," Byrne replied.
Mr Justice White then asked: "How many times have you made statements hinting you might have witnessed a stabbing?"
Byrne said: "I can't remember making a statement, Judge."
Meanwhile, Thompson was not in his mother's house at the time of Sunday night's petrol bomb attack and it is understood that his mother was the sole occupant of the house.
A senior source explained: "Mrs Thompson has allowed gardai to view the CCTV.
"It shows two young men in hoodies throwing what appears to be a bottle at the house."
This is not the first time that Thompson's family home has been targeted this year.
In the early hours of May 15, a viable pipe bomb was thrown at the back of the property.
An Army bomb disposal team was called out and made the bomb safe. No controlled explosion was carried out.