Sinn Féin has been left in an invidious position, writes Dan Keenan, Northern News Editor.
Last week Sir Reg Empey received a phone-call at his Ulster Unionist office in east Belfast. It was from a nationalist in Short Strand about the murder of Robert McCartney outside a city-centre pub at the end of January.
It was, he says, the first time he has ever received a call from the area about such a serious crime.
That such a caller would make such a call to an Ulster Unionist representative is evidence that Sinn Féin is "on the back foot", he says.
Republicans have no need to listen to Sir Reg's anecdotal evidence to realise the seriousness of the knifing of the popular 33-year-old father of two.
A letter in yesterday's Irish News from the murdered man's aunt was headlined "Murder cover-up may pen Sinn Féin's epitaph".
Mrs Margaret Quinn told the prominent nationalist newspaper: "Defying gangsters and murderers who demand that we keep quiet about the senseless slaughter of Robert by Shankill Butcher-types and psychopathic cowards disguised as our so-called 'protectors' is a very dangerous business."
She wrote in praise of Mr McCartney's sisters, themselves Sinn Féin supporters, who are publicly asserting a popular local belief that their brother was killed by an IRA member, although not one acting under orders.
They are equally convinced that a cover-up has been orchestrated to frustrate the PSNI inquiry and ensure that Sinn Féin is shielded from any political fall-out from the murder.
"Despite their unbearable grief, they tirelessly flag up the fact that, while Robert's murder may not have been 'sanctioned', it was [ her emphasis] committed by scum in the IRA who, by association, disgrace that entire organisation," wrote Mrs Quinn.
She further alleged that the subsequent cover-up and threats to witnesses emanated from the highest level of Sinn Féin and the IRA.
"For me, that makes them accomplices after the fact in my nephew's unjustifiable murder."
Graffiti writers have already daubed "PIRA scum" on the walls, not of the locality around Sir Reg's UUP office, but in Short Strand itself.
Arguably no party in the North street-level credibility or presence as high as Sinn Féin.
Whether such a revolt of sorts by graffiti artists and letter-writers points to a bottom-up revolution among the republican bedrock remains to be seen.
Certainly, senior Sinn Féin figures, and even P. O'Neill himself, are moving quickly to contain the anger at the murder of Robert McCartney after a drink-fuelled row in a pub one Sunday afternoon.
The IRA's statement, issued on Wednesday as a head of steam continued to build over the issue, is being seen as an attempt to facilitate the investigation of the murder without departing from the long-established position of not supporting the PSNI.
Short of calling for witnesses to go to the police, the O'Neill statement insisted: "No one should hinder or impede the McCartney family in their search for truth and justice - anyone who can help the family with this should do so".
For the family, this means going to the PSNI, and people like Sinn Féin's Gerry Kelly now seem happy to let them conclude that.
The North Belfast Assembly member also defined justice in this case as the suspects facing a court (that IRA members once refused to recognise), conviction and a jail sentence.
With one May election - for local councils - already declared, and another undeclared election - for Westminster - expected, the controversy is already extremely politically sensitive.
Public sympathy for a large financial institution such as the Northern Bank is, to say the least, limited. The theft of £26.5 million has even provoked a sense of "sneaking regard" for the engineers of such a daring, even breathtaking, plot.
But reaction to the murder of Robert McCartney is on a different and more human level. Sympathy on the streets for the articulate and valiant sisters of Robert McCartney is much more intense, and not just because an innocent life has been lost.
If the Short Strand syndrome shows anything, it is that public tolerance of IRA action, even in republican heartlands, is not limitless.
Sinn Féin's task seems to be to appear loyal to the IRA on the one hand and to the communities which elect it on the other.
With friction between the people and the IRA clearly in evidence, that task has just grown more dangerous and complex.