Sinn Féin's Chief Negotiator, Martin McGuinness, has said the sisters of Robert McCartney should not allow themselves to be manipulated by others.
Mr McGuinness said the McCartneys needed to be very careful they did not step over the line into party politics, which he said could do a huge disservice to their campaign to bring the killers to justice.
Mr McGuinness also said republicans suspected the PSNI was tailoring its investigation into the killing to cause maximum damage to Sinn Féin.
Earlier, Sinn Féin confirmed that a second party election candidate was in Magennis's bar near Belfast city centre on the night Mr McCartney was stabbed to death.
Deirdre Hargey, 23, is a community worker in Belfast and has been chosen as a candidate in the Laganbank area of Belfast for the local elections next May.
Today, the party said Ms Hargey was still inside Magennis's on the night of Sunday 30 January when the police arrived.
But she denied seeing the brawl that led to the knife attack which left Mr McCartney, 33, dying on the street outside.
The development comes two days after the 2003 Sinn Féin assembly election candidate, Cora Groogan, confirmed she was among around 70 people in the bar when the row that led to the killing began.
Ms Groogan said she has given a full statement to her solicitor.
