The Limerick mobster was released two weeks early from the city's prison following an eight-year-sentence imposed in 2017.
Collopy, along with his brother Kieran, had been caught red-handed cutting up a stash of heroin at a house in their Island Field stronghold.
The 48-year-old is considered to be the leader of the crime clan which played a significant role in the city's decades-long lethal underworld feud.
Kieran is also due for release in the coming weeks.
But they will each leave behind a son in prison, where it is suspected they used their connections to control the illegal drugs trade behind bars.
The Sunday World revealed last week how Kieran's son Tony was jailed for a drunken Taser gun attack during a pub brawl two years ago.
He was then seen on CCTV footage kicking a man in the head after he had fallen to the ground. The victim of the attack never made a complaint to Gardaí.
Brian's son Kenneth is serving a life sentence for the murder of Daniel Fitzgerald in 2009 when, aged just 19, he fired several shots from a Glock handgun.
The victim had no connection with crime whatsoever and was described in court in being in "the wrong place at the wrong time".
While Collopy senior has been behind bars the mob has still been the target of the Criminal Assets Bureau who have seized property.
The most recent tax demand totalled €1.3 million. In 2010, CAB however had to hand back €15,000 to Brian and his wife Maria after they claimed they had earned it legitimately.
They successfully claimed they had got it as a gift from the sale of horses and from her earnings from her ice-cream van.
CAB had previously seized the couple's home at Fedamore, Co. Limerick, and sold it for €225,000.
Kieran and Brian were jailed when they were caught red-handed packing €37,000 of heroin to be sold to wholesalers for sale in Limerick.
In March this year, Kieran Collopy lost his legal bid to keep the house in the Island Field which had been repossessed by the City Council.
The council acted after complaints about antisocial activity at the property gave them the legal grounds for the move.
Kieran Collopy claimed in court that he would have nowhere else to live on his release from prison except for the house on St Ita's Street, despite not having lived there since 2005.
The Collopy clan have been closely aligned with the Keane faction for decades.
Kieran and another brother Philip were targets of a murder plot in 2003 in which Kieran Keane was killed and Owen Treacy left for dead.
Attempts were made by the Dundon gang to force Keane and Treacy to call the Collopys in a bid to lure them into a lethal trap.
Philip Collopy and Kieran Keane were the main suspects for the fatal shooting of Eddie Ryan snr, in the Moose Bar in November 2000 which kicked-off the bloody gangland feud in the city
Philip Collopy had been feared as a gangland enforcer until his death in 2009 when he accidentally shot himself in the head while showing off a gun at a party.
Three of the brothers, Brian, Kieran and Damien, were previously jailed in 2011 after their bid to extort cash from a man backfired.