But what made their murders different to many other gangland killings was that the two had absolutely no involvement in organised crime.
They were executed by mistake -- casualties of a feud that has consumed the wider Coolock area for seven years.
Their 'crime'? To be seen driving a car like the one being used by two of the feud's chief protagonists, John Paul Brennan (31) and Jamie Clarke (23).
They have survived numerous attempts on their lives, including a gun attack last September. Clarke had a lucky escape after being shot in the leg outside a house in Coolock.
Two months later, members of the Coolock/Kilbarrack crime gang hatched a plan to keep their vehicle under surveillance.
It is believed that the gang used a criminal in his 30s from Kilbarrack to place a tracking device on the Toyota Avensis owned by tragic Mark Noonan.
It's not known how long this device was on the vehicle but on the night the cousins were murdered, it's thought they were stalked around Finglas for a number of hours before they were finally shot dead.
The suspected assassins, Kilbarrack men based in Northern Ireland, are considered to be among the most "dangerous and reckless" criminals in Ireland.
They have also been directly linked with the murder of small time crook James Perdue (22), shot dead in Donaghmede in June 2006 as well as the murders of innocent men Warren O' Connor (24) who was stabbed to death in January 2010 and Keith Fitzsimons, gunned down in June 2006 in another case of mistaken identity.
"Killing is a way of life for these thugs," said a source.
The double murder of Murphy and Noonan was just the latest installment in a bitter feud which started when a feared mob from the Coolock, Donaghmede and Kilbarrack areas had an internal dispute about the proceeds of a major security van robbery back in 2004.
The row spiralled into a number of other separate feuds over drug dealing turf, love rivalries and debts.
At the centre of it all is one of the capital's most notorious criminals, nicknamed The Panda by the media.
Considered to be one of Ireland's biggest drug dealers, The Panda has been successfully targeted by the Criminal Assets Bureau and is closely linked to JP Brennan and Jamie Clarke -- the intended targets of the Finglas double murder.
Brennan was previously lucky to escape with his life when he was cornered in his girlfriend's home in Kinsealy and shot in the leg and neck in January 2009.
Another of The Panda's closest associates is Paul 'Burger' Walsh (28) from Foxhill, Baldoyle who made a major settlement with CAB in October 2007.
On that occasion, the bureau confiscated a house in Swords, a mobile home in Curracloe, Co Wexford, €80,000 from a bank account and €39,000 that had been paid as a deposit on two apartments in Portarlington.
The High Court heard Walsh was a drug dealer who was engaged in large-scale drug-trafficking throughout the Dublin region.
CAB's investigation found that Walsh was a member of an organised crime gang in Dublin, the court heard.
The Panda has also been linked to feared criminal, David Goulding (32) of Whitechapel Grove, Clonsilla ,who was jailed for three years in February 2008 for interfering with the principal prosecution witness in an attempted murder trial.
The other side is led by two brothers whose drug supplier is an arch criminal based on the Malahide Road.
This shadowy crime figure -- who has barely any previous convictions -- is a veteran drugs trafficker who has made huge money from dealing but attracted little media attention.
Another key member of this gang is a notorious Tiger kidnap suspect from the area, now based in Co Cavan.
Their bitter rival Jamie Clarke -- who had also forged links with slain gang boss Eamon 'The Don' Dunne in the months before Dunne was killed -- is no stranger to the tragedy of gangland violence.
Jamie's older brother BJ was murdered when 15 shots were fired into a car in Artane, around 3am on May 7, 2009.
The chief suspects for murdering BJ Clarke are also the suspects for shooting the innocent cousins Murphy and Noonan in Finglas.
The month after BJ Clarke was gunned down, Traveller criminal Tommy Joyce (20), who was believed to have supplied the automatic weapon used in Clarke's murder, was shot five times in the head and chest outside his home at Grove Lane, Coolock
And then in January 2010, Tommy's older brother -- notorious drugs trafficker John Paul Joyce (30) -- was abducted, tortured and shot when members of The Panda's gang linked up with The Don's Finglas mob.
The last major incident linked to the gang warfare happened in late July when rival gangsters desecrated the grave of BJ Clarke.
The headstone on Clarke's grave was smashed up and had to be removed from Fingal Cemetery, Balgriffin, Co Dublin.
The attack led to an associate of Clarke's writing a letter warning that the "windy scumbags" who carried out the attack "will have nothing but bad luck".
The headstone incident happened just weeks before an associate of Brennan was slashed in broad daylight in the Henry Street area of the city centre.
Sources say that this shows the Coolock feud is very active.
As the foot soldiers continue to be involved in tat-for-tat violence, gardai believe that The Panda, originally from Kilbarrack but now mostly based in Spain, will continue to prevail.
Sources believe The Panda and a north inner city crime gang were involved in the high-profile murder of Anthony Russell (30) in the Ardlea Inn pub in Artane in April, 2008.
The psychopathic hitman used for this murder can't be named as he is facing charges.
He has been arrested and questioned twice by detectives about the murder of Russell, a criminal who lived at Cromcastle Court, Kilmore, and had strong links to the Christy Griffin crime syndicate.
It was the summer of 2008 when The Panda gained massive gangland notoriety. He enlisted convicted Ballyfermot hitman Eric 'Lucky' Wilson to dispatch of two of his former drug trafficking associates.Gardai believe the associates suffered terrible deaths after becoming the victims of a gangland double cross that July.
Tensions had spiralled out of control because The Panda owed his former boss, major league drugs trafficker David 'Babyface' Lindsay, a seven figure sum for drugs.
Sources say Lindsay decided to teach The Panda a lesson and ordered the murder of the gangster's close associate Anthony Foster, who was shot dead in the stairwell of flats at Cromcastle Court in July 2008.
But less than a week after Foster was murdered, The Panda engineered a diabolical double-cross that led to the murder of 'Babyface' Lindsay and his pal Alan Napper, last seen alive in Clane, Co Kildare.
Sources believe the feared duo were murdered in a house in Co Down after being savagely tortured. It's understood their bodies were cut up and dumped in the Irish Sea.
"After The Panda did that a lot of people were in fear of him," explained a source.
The last murder The Panda's gang has been linked to is that of Sean Winters, a drug dealer, shot dead in Portmarnock last September.
It is understood that the gang enlisted a local Real IRA team to murder Winters, a former close associate of Lindsay and Napper whose reckless criminal behaviour was causing concern to The Panda's organisation.
A number of senior Real IRA men were arrested in the aftermath of Winters' murder but all were released without charge.
Apart from all this gangland terror, a separate feud has been brewing among Traveller criminals the Coolock area throughout 2011.
As in the neighbouring suburb of Finglas, the Traveller feud has seen multiple violent incidents including and homes and caravans being firebombed.
The Herald revealed that some of the Coolock Traveller criminals, who had been involved in extortion, had been threatened with death by the Real IRA for using the dissident organisation's name.
Among the Traveller criminals under "active threat" are three men who were arrested by armed officers from the Special Detective Unit in July over a botched extortion racket in north Co Dublin.
The Coolock Traveller criminals are strongly connected to a jailed senior dissident who received a severe beating from other dissident Republicans recently in Portlaoise Prison.