A SINN Féin senator is facing calls to resign after retweeting a message from a government parody account calling a murdered prison officer a `sadist'.
Senator Máire Devine, Sinn Féin spokeswoman on health and mental health, has since removed the message from her Twitter stream and the party has said it will be asking her for an explanation.
Brian Stack was chief officer at Portlaoise Prison when he was shot dead by the IRA while leaving a boxing match in Dublin in 1983.
He died from his injuries 18 months later.
His son Austin Stack highlighted Ms Devine's retweet of the message on the social media site which referenced his criticism of Taoiseach Leo Varadkar's attendance of an event, alongside the former Sinn Féin president where New York Mayor Bill de Blasio proclaimed Gerry Adams Day.
The tweet read:
`Taoiseach Leo Varadkar has congratulated Gerry Adams after the people of New York celebrated #GerryAdamsDay.
`Leo had no response to criticism in the #Sindo from a #SaveThe8th Fianna Fáil son of a sadist prison officer.'
?Mr Stack displayed the message to his followers, saying Sinn Féin "must immediately expel (Máire Devlin) for this disgusting tweet.
"No apologies will be accepted by myself or my family for this gross defaming of a man they murdered."
Ann Travers, whose sister Mary was killed by the IRA in 1984, branded the retweet "abhorrant" and called on the party to "take prompt action".
Mr Stack said it was "incredible that a political representative is revictimising the son of an IRA victim".
"I had to watch my father die after he was shot by Provos."
He asked whether Sinn Féín leader Mary Lou McDonald would seek her resignation.
A Sinn Féin spokesman told Dublin media: "The tweets are not acceptable for a Sinn Féin elected representative. If a breach of our social media guidelines is proven then disciplinary action will follow."
