The 35-year-old may have also played a role in sourcing weapons for the Hutch gang through the gunman, nicknamed “Flat Cap”, after he was photographed wearing the hat following the hotel assault on February 5.
Senior gardaí now fear the murder of a Real IRA member in Dublin’s north inner city could drag the dissident group into the spiralling feud.
Mr Barr’s death at Sunset House pub was one of two fatal shootings in the city on Monday night, with the unrelated murder of one-time minor criminal Tom Farnan in Clondalkin, west Dublin, two hours later.
Garda security chief, Assistant Commissioner John O’Mahoney, urged those involved in the feud to “take stock” and appealed to them to realise that taking “one life after another” was not going to solve anything.
Six people have so far been murdered in the Kihanan-Hutch feud, one in Spain and five in Dublin since February.
The Kinahan cartel is suspected in five of the murders and the Hutch network in one.
Assistant Commissioner O’Mahoney yesterday revealed there was an armed patrol “around the corner” from the Sunset House at the time of the murder.
He said that this was “indicative of the challenge” they faced in preventing attacks by determined gunmen.
Mr Barr, from Strabane, Co Tyrone, moved to Dublin a number of years ago and had addresses in Ballymun and Finglas.
He was shot dead in the Sunset House, where he worked, at around 9.30pm on Monday.
Garda Superintendent Dan Flavin of Mountjoy Garda Station — who is leading the investigation — yesterday said two masked men, described as “skinny”, entered the pub and fired a number of shots, fatally wounding Mr Barr.
He said the gunmen escaped in a silver Audi A6, registration 04C 17738, and drove north towards Drumcondra, where they abandoned the car.
They then got into another silver car.
Supt Flavin appealed for witnesses to contact gardaí on 01 6668600 or the Garda confidential line on 1800 666111.
Just over two hours later, father of one Tom Farnan, aged 37, was shot up to four times in the upper body as he answered the front door of his house at Kilcrohan Close, Clondalkin.
Supt Brendan Connolly of Clondalkin Garda Station said gardaí arrived within two minutes and tried to save the man’s life, as did paramedics when they arrived, but to no avail.
He said a lone masked gunman appeared to have been involved, dressed all in black.
He headed for the Grand Canal and Lock View Road.
Supt Connolly appealed for witnesses to ring the station on 01 6667600 or the confidential line.
He said the victim would have been known to gardaí “at an earlier stage in his life” and said gardaí were exploring a number of possible motives for the attack.
Deputy Commissioner John Twomey expressed sympathies to families and friends of both victims.
He said that “no stone will be left unturned” in bringing the perpetrators to justice.
He said he was aware of the “trauma and distress” such incidents had on local communities.
He insisted — contrary to some reports from local gardaí — that there has been “no reduction in patrols” in communities affected by the feud.