Paula McCartney said her family was considering all options as they continue their fight to see the killers put on trial and behind bars.
The 40-year-old, from Short Strand in Belfast, said: “As my family continues the quest to have the men who brutally murdered my brother put behind bars, we have to look at all the options available to us. There is a possibility of contesting the local government elections, but a decision like that is a long way away, at this stage.”
She said the family are determined to keep the pressure on the people who fatally stabbed Robert outside a bar in Belfast three weeks ago.
Ms McCartney also claimed the killers were not being shunned by the republican movement.
One of those alleged to be centrally involved in the killing was seen by one of her family talking to a potential key witness.
“This is a clear indication these cut-throat murderers are not being shunned by the republican movement,” said Ms McCartney
The Westminster and local elections in the North are set to take place later this year. The murder of Mr McCartney has led to an unprecedented public display of anger within republican communities against the criminality of some members of the IRA.
More than 1,000 people from the Short Strand area and beyond took part in a vigil for the dead man as the family demanded that the IRA and Sinn Féin not hinder the police investigation into the murder.
Sinn Féin’s representative in the area, the city’s Deputy Lord Mayor Joe O’Donnell, has indicated he will not stand in the local election.
Mr O’Donnell said he backs the McCartney family and would go whatever lengths to help them.