The family of Det Garda Jerry McCabe and his garda colleagues said they were simply not interested in McCauley.
"We have no interest in that man," was the softly spoken, but firm response from a family spokesperson of widow Ann McCabe.
The general secretary of the Garda Representative Association, PJ Stone, also said it was not something that concerned or interested them.
McCauley, 37, from Strabane, Co Tyrone, is serving 14 years for the manslaughter of Garda McCabe, a 52-year-old father of five, during an armed robbery in Adare, Co Limerick in 1996 by members of the IRA.
Three of McCauley's colleagues Jeremiah Sheehy, from Rathkeale, and Michael O'Neill and Kevin Walsh from Patrickswell, all Co Limerick were also convicted for the death.
In what is seen as a political embarrassment for Sinn Féin, McCauley is to marry Sinn Féin councillor Pauline Tully.
The wedding will take place at Kilnaleck in Cllr Tully's Co Cavan constituency.
McCauley, along with his three colleagues, is currently been held at a low security section of Castlerea Prison in Co Roscommon.
He has been granted overnight temporary release for the wedding. A spokesman for the Prison Service said it did not comment on the granting of temporary release prior to the event, and tend not to do so afterwards either.
The spokesman added: "The concession of temporary release has been in force for decades."
He said the process was formalised in the Criminal Justice Act 1960, which established that temporary release could be granted for humanitarian, compassionate and resocialisation purposes.
While Garda McCabe's killers have not been deemed by the Government as IRA members who qualify for early release under the Good Friday Agreement which is being challenged in the courts they have received concessions while in Castlerea for good conduct.
None of McCauley's colleagues have been granted temporary release to attend the wedding.
A decision to grant temporary release to a prisoner of such notoriety as McCauley would have to be cleared at the very top, by the Minister of Justice or the relevant Cabinet committee.
It is understood McCauley revealed to prison authorities his reason for seeking temporary release when he made his application.
Several hundred prisoners are granted temporary release every year in the Irish prison system.