Luigi Forte, who has 116 previous convictions, is a top target for gardai for his involvement in car thefts, burglaries and organised crime.
The 33-year-old was yesterday sentenced to nine months in prison after pleading guilty to careless driving causing the death of Dylan Byrne.
The young man was a back-seat passenger in a red Renault Megane which left the road and hit a ditch near Boyle, Co Roscommon, in the early hours of August 10, 2016.
Mr Byrne, who was originally from Crumlin, suffered serious injuries and was brought to Sligo University Hospital. He was pronounced dead a short time later.
Forte, who was driving the car, needed hospital treatment and was later arrested and questioned for several hours at Carrick-On-Shannon Garda Station in Co Leitrim.
The notorious criminal, of New Street Gardens in Dublin's south inner city, was later charged over the incident.
Forte was sent forward to Roscommon Circuit Court after appearing at Carrick-on-Shannon District Court last November. Yesterday at his sentencing hearing, the court heard how his vehicle briefly became airborne, severing a stop sign and coming to a halt 27 metres from the point of impact of the collision.
The car had been travelling from Sligo in the direction of Carrick-on-Shannon.
In a victim impact statement, Mr Byrne's mother Tracy Brady said her family had been torn apart by his death, and the man who was driving should not have even been behind the wheel as he was banned.
She described her son "as a beautiful young man", who discovered two weeks before his death that he was to become a father. Mrs Brady said he was not an associate of Forte.
Judge Keelan Johnston called for a new campaign on seat-belt safety to be launched by the Road Safety Authority, after hearing evidence that Mr Byrne was not wearing one.
"The proof of this is evidenced by the fact that both the accused and the front-seat passenger received no injuries in the accident because they were both wearing seat-belts," he told the court. "The message needs to go out loud and clear that no-one should attempt to drive or travel as a passenger in a car without employing their seat-belts."
Judge Johnston noted that the maximum prison term that could be imposed for careless driving causing death was two years. Taking a number of mitigating factors into account, he sentenced Forte to 12 months in jail, with the final three months suspended.
Forte is well known to gardai in south Dublin as well as national units tasked with investigating people involved in the stolen motor trade.
He is considered the "right-hand man" of a Crumlin-based crime boss who is one of the capital's most active criminals.
This individual, who is also aged in his 30s, has survived at least three attempts on his life in recent years.
Only last month, Forte was arrested by detectives from Crumlin Garda Station over a cash-in-transit robbery in Errigal Road, Drimnagh, last May. He was later released without charge after being questioned about the getaway car used in the robbery.
A source last night told the Herald
that the jailing of Forte was a relief, albeit a brief one, for gardai.
"He is a serious criminal and has been linked to organised criminality for some time," the source said.
"It's a relief that he has been jailed, although only for nine months, and investigations are ongoing into his associates for a wide range of crimes such as operating car theft rings."
Last Saturday, detectives from Terenure Garda Station and the Stolen Motor Vehicle Investigation Unit carried out a massive raid on a car parts business in which 19 stolen engines were seized.
The operation, in west Dublin, targeted a criminal who is being provided with stolen high-end cars by Forte's associates.