This week he was convicted, in a landmark judgement, of running a drugs ring from his Portlaoise prison cell.
As a detective superintendent I personally encountered Rattigan. As you can imagine, I found him a very unsavoury character, not least because he tried to kill some of the officers who worked under my direction.
That happened 10 years ago today, when Rattigan opened fire on my colleagues in their patrol car as they pursued him on La Touche Road in Bluebell.
He fired with a shotgun from the rear window of the car he was in. Luckily, no officer was injured and Rattigan was chased and captured.
It was the first time Rattigan had come to widespread public attention. It would not be the last.
But of all the crimes I encountered that were perpetrated by this criminal, the most chilling involved a murder he planned that I investigated with my team a year later.
And like the drugs case this week, Rattigan planned it from a prison cell.
On the night of February 25, 2004, at Grays Public House, in Newmarket Square, just off Cork Street in Dublin's south inner city, a terrible execution was about take place.
It resulted in the death of 24-year-old Paul Warren. While he was socialising, two masked and armed men came into the pub, one stood at the front door covering the customers present while the other walked towards Paul Warren. Warren made a run towards the toilet but while trying to escape he was shot in the back.
Warren ran into a cubicle and jammed the door in a further effort to evade his assassin but the gunman pushed his arm through the door and shot Warren in the face, fatally.
Paul Warren died where he lay. The two gunmen bolted from the pub.
Warren was a criminal who lived in a league a lot lower than gangland, but he had mixed with the wrong people.
It is important to give the reader a little of the background to this. In 2001, a criminal named Declan Gavin was murdered on the Crumlin Road, Brian Rattigan was charged with this murder. In July 2002, Joseph Rattigan was murdered on Cooley Road in Drimnagh, a brother of Brian Rattigan.
It was believed this second murder was in retaliation for the first one.
The killings launched a feud which still goes on. It has resulted in many more deaths.
On the night of Joseph Rattigan's killing, Paul Warren was the last person with him and it is widely thought that Warren was murdered for setting up Joseph Rattigan.
After the pub shooting, we received confidential information to suggest that a man using the nickname Tipper shot Warren. Tipper was later identified as one Gary Bryan.
We then arrested another man, Jonathan Mooney. During his detention, he admitted to getting mobile phone calls from a man in Mountjoy Prison asking him how Warren was dressed and his location on the night.
He was also directed by the Mountjoy prisoner to let him know if Warren left the pub.
He received five calls from the same man and gave him all the sought information.
He later said that he knew Warren and the man on the mobile phone were mortal enemies, but he still gave the information.
When asked what he thought would happen, he said just a few slaps.
A short time later Mooney got another call on his girlfriend's phone and the question posed this time "Did Warrener get killed?"
The man in prison told Mooney to get rid of the phone. Mooney was later arrested and convicted of his part in the shooting.
Who was the mysterious man on the prison phone?
None other than Brian Rattigan, 'King Ratt' himself. Within a few weeks, I issued warrants under Section 29 of the Offences Against the State Act to search specific cells in Mountjoy Prison used by him.
This was the first time that prison cells were searched under such legislation. During the search, parts of phones, amongst other items, were found. Unfortunately, they did not prove anything of evidential value. Gary Bryan was later charged with the murder of Paul Warren. At the Central Criminal Court he was found not guilty after a witness, Bryan's ex-girlfriend Valerie White, withdrew her statement. Bryan was later shot dead in Drimnagh, another victim of the feud engaged in by 'King Ratt'.
This is just one short story about the killer and drug dealer known as Brian Rattigan – but it provides an insight into how this gangster operates and why he's one of the most dangerous men in the country.
He is serving life for another feud-related murder and that, along with this week's drug conviction, will hopefully ensure he never sees the light of day in the outside world again.
PJ Browne is a former detective superintendent who investigated the activities of Brian Rattigan and his gang